NATIONAL 325776 Rear Crankshaft Seal 614046654280

( Brand: National ), ( Manufacturer Part Number: 325776 ), ( Product Type: Engine ), ( UPC: 614046654280 ), ( Fitment Type: Direct Replacement ), ( Partslink Number: 10101164, 4316315r1, 3138701r91, 4316316r1, 3228457r1 ), ( Compatible Make S : Chevrolet, Gmc, Workhorse ), ( Compatible Model S : K2500 Suburban, C2500 Suburban, R2500 Suburban, C2500, K2500 ), ( Fitnote: Enginevinname ), ( Product Subtype: Crankshafts ), ( Placement On Vehicle: Rear ), ( Type: Seals Gaskets ), ( Product Details: Engine Crankshaft Seal ), ( Engine Version: 454 Chevy Big Block V8 Gen Iv-vi ), ( Department: Replacement )

Review NATIONAL Chevy Rear Crankshaft Seal fits SUBURBAN K2500 1992–1999

The **National 325776 Rear Crankshaft Seal** is a high-performance, precision-engineered replacement part designed specifically for Chevrolet K2500 Suburban models built between 1992 and 1999, featuring the iconic 7.4L V8 engine (L36/L37/L48/L49/L56/L57). This seal is meticulously crafted to meet or exceed OEM specifications, ensuring a reliable, long-lasting solution for preventing oil leaks at the rear main bearing housing. Constructed from high-quality, oil-resistant nitrile rubber with a reinforced steel backing, the seal is engineered to withstand the extreme pressures and temperatures generated by the powerful V8 engine, providing superior durability and resistance to degradation over time. The precision-machined lip design ensures a tight, consistent seal against the crankshaft, minimizing the risk of leaks while reducing friction and wear on the crankshaft itself. Whether addressing a slow oil leak, preparing for a major overhaul, or upgrading an existing engine, this seal delivers the performance and reliability needed to keep your Suburban running smoothly for thousands of additional miles. National s reputation for quality and compatibility makes this an ideal choice for both professional mechanics and DIY enthusiasts seeking a dependable, long-term fix.

Buying the **National 325776 rear crankshaft seal** for a **1992 1999 Chevy K2500 Suburban** has its advantages and drawbacks. Below is a detailed breakdown of the pros and cons, followed by a conclusion and recommendation.

---

### **Pros of buying a National 325776 Seal**

1. **Compatibility and Fitment**

The National 325776 is a direct replacement for the OEM rear crankshaft seal in GM s **L31, L36, and L48** engines, which power the 1992 1999 K2500 Suburban. It is designed to match the original dimensions, ensuring a proper fit without modifications. This reduces the risk of installation errors that could lead to leaks or premature failure.

2. **Quality Materials**

National is a well-established manufacturer known for producing durable seals, gaskets, and aftermarket automotive parts. Their crankshaft seals are typically made from high-quality rubber compounds reinforced with fabric or metal, which provides better resistance to oil, heat, and wear compared to cheaper alternatives. This can extend the seal s lifespan, especially in applications with higher stress or exposure to contaminants.

3. **Widely Available and Easy to Source**

The National 325776 is a stock part for many GM vehicles, making it readily available through auto parts stores (e.g., AutoZone, O Reilly, RockAuto), online retailers (Amazon, RockAuto, eBay), or directly from National s distributors. Its popularity ensures consistent stock and quick shipping in most cases.

4. **Cost-Effective for the Lifespan**

While the upfront cost may be slightly higher than the cheapest generic seals, the National 325776 often lasts longer and performs better, reducing the likelihood of needing a replacement soon after installation. This can save money in the long run by avoiding repeated repairs.

5. **Positive User Feedback**

Many reviews from owners of similar GM trucks (e.g., Silverado, Tahoe) report that the National seal holds up well under normal driving conditions, especially when installed correctly. Fewer complaints about leaks or early failure compared to no-name brands are common in forums and review sites.

6. **Compatibility with Common Modifications**

If your Suburban has undergone modifications like a performance tune, turbocharging, or increased oil pressure, the National seal s robust construction may handle the additional stress better than weaker alternatives. However, extreme modifications (e.g., forced induction) could still require additional precautions (e.g., proper torque on the flywheel housing bolts).

7. **Warranty and Return Policies**

National and most major retailers offer warranties or return policies, providing some recourse if the seal fails prematurely due to a defect. This adds a layer of confidence for buyers who want assurance of their purchase.

---

### **Cons of buying a National 325776 Seal**

1. **Higher Upfront Cost**

The National 325776 is priced higher than generic or no-name seals (often by $10 $20 or more). For budget-conscious buyers, this can be a significant drawback, especially if they are working on a tight budget or have multiple parts to replace.

2. **Potential for Counterfeit or Low-Quality Stock**

While less common than with ultra-cheap brands, there is still a risk of purchasing a counterfeit or subpar "National" seal, particularly when buying from third-party sellers (e.g., eBay, Amazon third-party vendors). Always verify the seller s reputation and check for authenticity markings (e.g., part numbers, packaging details). Buying directly from RockAuto or a trusted retailer minimizes this risk.

3. **Installation Challenges**

Replacing a rear crankshaft seal requires removing the transmission, flywheel housing, and sometimes the flexplate, which can be labor-intensive. While the National seal itself is designed for easy installation, the process demands mechanical skill and patience. Improper installation (e.g., over-torquing bolts, not cleaning surfaces) can void the seal s effectiveness and lead to leaks.

4. **Limited Longevity in Harsh Conditions**

Although the National seal is durable, extreme conditions (e.g., extreme heat, heavy towing, frequent off-roading, or contaminated oil) can still cause premature wear. In such cases, the seal may not last as long as advertised, and additional maintenance (e.g., frequent oil changes, using high-quality oil) is necessary.

5. **Mixed Reviews on Durability in Aggressive Applications**

While the National seal performs well in standard driving conditions, some users report that it may not last as long in high-performance or heavily modified engines. For example, vehicles with turbochargers or high RPM usage might experience seal failure sooner than expected, depending on the quality of other components (e.g., oil pump, flywheel bolts).

6. **Potential for Overkill in Mild Applications**

If your Suburban is used primarily for light-duty tasks (e.g., daily commuting, occasional towing), the National seal s higher cost may not be justified. In such cases, a mid-range brand (e.g., Fel-Pro, Goodyear) could offer a good balance of quality and price.

7. **Dependence on Proper Maintenance**

- Using the correct oil viscosity and type (e.g., GM dexos1 or equivalent).

- Changing the oil and filter at recommended intervals.

- Ensuring the flywheel housing bolts are torqued correctly (typically 80 100 ft-lbs in sequence).

Failure to adhere to these practices can reduce the seal s lifespan regardless of brand.

---

### **Conclusion**

The **National 325776 rear crankshaft seal** is a strong choice for most **1992 1999 Chevy K2500 Suburban** owners due to its reliability, compatibility, and durability. It strikes a balance between quality and affordability, making it suitable for both everyday drivers and those who engage in moderate towing or light modifications. However, it is not the absolute best option in every scenario its higher cost and potential overkill for mild applications must be weighed against the benefits.

For **high-performance or heavily modified vehicles**, consider pairing the National seal with additional precautions (e.g., using a high-quality oil pump, ensuring proper flywheel bolt torque, and monitoring oil pressure). In contrast, for **budget-conscious buyers or light-duty use**, a mid-tier brand like **Fel-Pro or Goodyear** may offer a cost-effective alternative without sacrificing too much longevity.

---

### **Recommendation**

- You prioritize durability and want a seal that is less likely to fail prematurely.

- Your Suburban is used for moderate towing, frequent driving, or has undergone minor modifications.

- You are willing to invest in a higher-quality part for long-term reliability.

- You plan to install it yourself or have a trusted mechanic perform the job with proper precautions.

- You are on a tight budget and the Suburban is used primarily for light-duty tasks.

- You are unsure about the installation process and prefer a slightly cheaper option with similar reviews.

- You have access to a mechanic who can ensure proper installation and maintenance.

Always verify the authenticity of the seal, especially when purchasing online. Check for the correct part number, packaging details, and seller reviews. Additionally, pair the seal with a **high-quality oil filter** and **proper oil** to maximize its lifespan. If your vehicle has high mileage or signs of oil leaks elsewhere, address those issues first to prevent further contamination.

Details:

Compatible with wide range of fluids. Specifications: Thickness: 0.394. Designed utilizing the latest technology, this product by National features premium quality and will perform better than advertised. Material: .

The finest quality at a great price. Order from the comfort of your home or office. width : 0.394. Inside Diameter: 4.331.

Rear Crankshaft Seal 325776 by National.

part #: 325776 prices

• $33.99-$57.99

specifications cranshafengin:

• for models: K2500, Suburban
• for makes: Chevy
• for years: 1992-1999
• brand: National
• mpn: 325776
• product type: Engine
• upc: 614046654280
• fitment type: Direct Replacement
• partslink number: 10101164, 4316315r1, 3138701r91, 4316316r1, 3228457r1
• compatible make s : Chevrolet, Gmc, Workhorse
• compatible model s : K2500 Suburban, C2500 Suburban, R2500 Suburban, C2500, K2500
• fitnote: Enginevinname
• product subtype: Crankshafts
• placement on vehicle: Rear
• type: Seals Gaskets
• product details: Engine Crankshaft Seal
• engine version: 454 Chevy Big Block V8 Gen Iv-vi
• department: Replacement

seller cranshafengin:

• city: Saint Paul, Minnesota
• # reviews: 159505
• rating: 99.2%

payments cranshafengin:

• credit card: Discover
• wallet: Google-pay
• other

shipping cranshafengin:

• cost: $19.00
• carrier: FedEx
• class: Standard
• transit: 2-6 Days
• service: FedEx Ground / FedEx Home Delivery
• type: Calculated

general cranshafengin:

• condition: New
• Car Truck Parts Accessories > Engines Engine Parts > Crankshafts

offer cranshafengin:

• sold: 0
• options: Ship-to-home
• quantity: 4
• started: May 20, 2026
• availability: In Stock

returns cranshafengin:

• policy: Returns Accepted
• paid by: Seller
• time: 30 Days

National 325776 Is Similar To:

• 1021v National Rear Engine Crankshaft 614046153431 (41.3% similar) Out of the seal and other wheel-end components. Don't just repair a leak, prevent future problems with National oil seal...(October 10th, 2017)
• 224660 National Bearings Oil Seal 724956233557 (32.5% similar) Standard size excellent resistance to petroleum-based oils and fuels, water alcohol good acids bases, except those with a strong oxidizing effect temperature range: -40. C manufacturer federal-mogul brand National bearings model NUMBER224660 upc: 57 weight. Our satisfaction guarantee all of products...(January 24th, 2018)
• 229005 National New Engine Crankshaft 724956076116 (41.3% similar) Multi purpose seal. Provides good low temperature capability. Footnote: counter-clockwise-spiral lip design. Design type: spring loaded multi-lip. Delivers quality and reliable performance for every type of repair. Low swell in hydrocarbon fluids. Vehicles sold outside of the USA may be different, ...(October 3rd, 2017)
• 229010 National Rear Inner Wheel 724956076123 (29.3% similar) 335 width mm: this part is engineered to meet OE specs perfectly fit your vehicle. This innovation aggressively deflects dirt, liquid, and other contaminants that can lead to premature seal bearing damage diminished wheel-end performance. Design type: spring loaded multi-lip good dry heat ...(November 10th, 2017)
• 2377 National New Engine Crankshaft 724956077168 (42% similar) Design type: spring loaded multi-lip. Shipping labels may only be applied to a separate, outer box. Delivers quality and reliable performance for every type of repair. Temperature range: 40 deg f to 225 c 107. Multi purpose seal. Material: floury-elastic. Vehicles sold outside of the USA may be ...(October 14th, 2017)
• 239155 National Oil Seals Seal (27.7% similar) ...(July 20th, 2018)
• 2692 National New Engine Crankshaft 724956084043 (42% similar) Provides good low temperature capability. Low swell in hydrocarbon fluids. Multi purpose seal. Material: polyacrylamide. Design type: spring loaded multi-lip. Delivers quality and reliable performance for every type of repair. Series: 2000 . Temperature range: 40 deg f to 225 c 107. Footnote: ...(October 14th, 2017)
• 2942 National New Engine Crankshaft 724956085637 (42% similar) Delivers quality and reliable performance for every type of repair. Multi purpose seal. Vehicles sold outside of the USA may be different, even if they have same make and model name. Temperature range: 40 deg f to 225 c 107. Footnote: clockwise-spiral lip design. Design type: spring loaded multi-lip...(October 14th, 2017)
• 355660h National Oil Seals Seal 614046236912 (24.3% similar) ...(July 20th, 2018)
• 450867 National Seal 724956132119 (25% similar) 437 width mm: 11. Design type: spring loaded single-lip provides good low temperature capability swell in hydrocarbon fluids range: 40F to 225F 40C 107C engineered for performance, National oil seals deliver superior protection and long service life thanks premium material construction a patent-...(November 10th, 2017)
• 452261h National New Engine Crankshaft 724956234387 (41% similar) Temperature range: 40 deg f to 225 c 107. Housing bore inch: design type: spring loaded multi-lip. Provides good low temperature capability. Shipping labels may only be applied to a separate, outer box. Multi purpose seal. Vehicles sold outside of the USA may be different, even if they have same ...(October 13th, 2017)