GENUINE GM PARTS 12665380 Engine Crankshaft 195491234901

( Brand: Genuine Gm Parts ), ( Manufacturer Part Number: 12665380 ), ( Manufacturer Warranty: 1 Year ), ( Type: Engine Crankshaft ), ( UPC: 195491234901 )

Review GENUINE GM PARTS Engine Crankshaft

The **GM 12665380 Engine Crankshaft** is a precision-engineered component designed for high-performance and durability in General Motors small-block V8 and LS-series engines, specifically tailored for applications requiring enhanced reliability and longevity. Crafted from high-grade forged steel, this crankshaft is built to withstand the intense stresses of high-revving engines, delivering smooth operation and exceptional power output while maintaining structural integrity under extreme conditions. The design incorporates a robust main journal and rod journal configuration, optimized for balanced weight distribution to minimize vibration and maximize efficiency, ensuring consistent performance even under heavy loads or aggressive driving conditions. With a meticulously machined surface finish, the crankshaft features precision-ground journals and counterweights that reduce friction and wear, extending the life of bearings and other critical engine components. This part is engineered to meet or exceed OEM specifications, making it an ideal replacement for stock cranks in both stock and modified engines, including those used in muscle cars, performance trucks, and high-performance street and drag applications. Whether restoring a classic GM engine or upgrading a modern performance build, the **12665380 crankshaft** provides the strength and precision needed to handle high RPMs, aggressive camshaft profiles, and forced induction without compromising durability. Built to exacting standards, it ensures seamless integration with GM s LS-series and small-block V8 engine families, offering a perfect blend of power, reliability, and longevity for enthusiasts and professionals alike.

### **Pros and Cons of Buying a GM 12665380 Engine Crankshaft**

The **GM 12665380** crankshaft is a critical component for engines like the **LS1, LS2, LS3, and LS6** (depending on the application). Below is an analysis of its advantages and drawbacks, followed by a conclusion and recommendation.

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### **Pros of Purchasing a GM 12665380 Crankshaft**

1. **OEM Quality and Reliability**

- GM s original crankshafts are engineered to strict tolerances, ensuring durability and performance. They are built to match factory specifications, reducing the risk of premature failure.

2. **Compatibility with High-Performance Applications**

- Many aftermarket tuners and engine builders prefer GM s original crankshafts because they are designed to handle higher RPMs and torque loads, especially in forced-induction setups. The **LS3/LS6** versions, in particular, are known for their strength in high-output applications.

3. **Warranty and Support**

- Purchasing from an authorized GM parts distributor or a reputable aftermarket supplier often comes with a warranty (typically 1 3 years). This provides peace of mind in case of defects.

4. **Ease of Installation**

- GM crankshafts are designed to fit standard LS engine blocks without extensive modifications. They come with proper balancing and machining, reducing the need for additional work.

5. **Resale Value and Authenticity**

- If you plan to restore or sell the engine later, an OEM crankshaft retains higher value than aftermarket alternatives. Buyers often prefer genuine GM parts for authenticity.

6. **Balanced and Precision-Machined**

- GM crankshafts undergo rigorous balancing and dynamic testing to ensure smooth operation. This minimizes vibration and reduces wear on bearings and other components.

7. **Support for Custom Engine Builds**

- Whether you're building a **street/strip engine** or a **high-performance race engine**, GM s crankshafts are a trusted choice. They are often used in **LS swaps** and **big-block applications** due to their robustness.

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### **Cons of Purchasing a GM 12665380 Crankshaft**

1. **Higher Cost Compared to Aftermarket Alternatives**

- GM crankshafts are more expensive than many aftermarket options. Prices can range from **$500 to $1,500 **, depending on the version (e.g., LS3 vs. LS6). Aftermarket cranks (from brands like **Crane, JE, or Scat**) may offer similar performance at a lower price.

2. **Potential for Counterfeit or Salvaged Parts**

- The used market is flooded with **salvaged or re-machined cranks** that may not be genuine. Buying from untrusted sources risks receiving a **rebuilt or low-quality part**, which could lead to failure.

3. **Longer Lead Times**

- GM parts distributors may have limited stock, leading to **extended wait times** (weeks to months). Aftermarket suppliers often have faster turnaround times.

4. **Overkill for Stock or Mild Modifications**

- If you re running a **stock or lightly modified engine**, an OEM crankshaft may be unnecessary. Aftermarket cranks with similar (or better) specs can be more cost-effective.

5. **Weight Considerations**

- GM crankshafts are **heavier** than some aftermarket options, which can slightly reduce acceleration in high-performance applications. Lighter cranks (e.g., **Crane s 6.160" stroke**) may be preferred by some builders.

6. **Limited Customization**

- Unlike aftermarket cranks, GM parts do not offer **custom stroke lengths, counterweights, or material variations** (e.g., forged vs. cast). If you need specific modifications, aftermarket may be the better choice.

7. **Potential for Misalignment Issues**

- If the engine block or bearings are worn, an OEM crankshaft may not perform optimally. Proper **block inspection and bearing replacement** are essential for long-term reliability.

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### **Conclusion**

The **GM 12665380 crankshaft** is a **high-quality, reliable choice** for serious engine builders, especially those working on **LS-based engines with high performance demands**. Its **OEM backing, precision machining, and compatibility with aftermarket upgrades** make it a strong option for **restorations, swaps, and high-RPM applications**.

However, if you are on a **tight budget, building a stock engine, or seeking custom modifications**, an **aftermarket crankshaft** (from reputable brands like **Crane, JE, or Scat**) may be a more practical choice. The key is ensuring the **source is trustworthy** whether buying new from GM or a verified aftermarket supplier.

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### **Recommendation**

- You are restoring a **high-mileage LS engine** and want **maximum reliability**.

- You are building a **high-performance engine** (forced induction, big bore, or high-RPM applications).

- You prioritize **authenticity and warranty coverage** for resale or long-term use.

- You have **verified the part is new and not salvaged** (purchase from **GM dealers, Summit Racing, or eBay verified sellers**).

- You are on a **budget** and can find a **high-quality alternative** (e.g., **Crane 6.160" or JE forged crank**).

- You need **custom specifications** (e.g., lighter weight, different stroke length).

- Your engine is **stock or mildly modified**, and an OEM crank is unnecessary.

**Final Tip:** Always **inspect the crankshaft for cracks, balance marks, and machining quality** before installation. If rebuilding an engine, **replace bearings, rods, and seals** to ensure longevity.

Details:

High-value items are usually sent with signature-delivery requirements. If you do, our experts will hand-verify compatibility before shipping. See below for instructions. 12665380: Genuine GM Parts: Engine Crankshaft.

Changed My Mind. Just Didn't Like it. This part fits vehicles made in the following years 2019 ,2 020. Add details like Tried to install this part, and it didn't fit. Request a Return.

Found a Better Price.

part #: 12665380 prices

• $1217.21-$1226.33

specifications cranshafengin:

• brand: Genuine Gm Parts
• mpn: 12665380
• manufacturer warranty: 1 Year
• type: Engine Crankshaft
• upc: 195491234901

returns cranshafengin:

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

payments cranshafengin:

• other
• credit card: Visa
• wallet: Apple-pay

seller cranshafengin:

• rating: 99.2%
• city: Garland, Texas
• # reviews: 19119

general cranshafengin:

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

offer cranshafengin:

• options: Ship-to-home
• started: May 15, 2026
• availability: In Stock
• quantity: 5
• sold: 0

shipping cranshafengin:

• type: Fixed
• class: Standard
• service: Standard
• transit: 19-29 Days
• cost: $0.00

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