CHEVROLET TRUCK 303.GM8X10 Gm Ls Iv Crankshaft 5.3L 6.0L 6.2L 58X 125521185809
fits make: Chevrolet. year: 2010.
( Brand: Chevrolet Truck ), ( Part Type: Crankshaft ), ( Conditions Options: 5.3l 6.0l 6.2l 58x Crank ), ( Genuine Oem: Yes ), ( Ipn: 303.gm8x10 )
Review CHEVROLET TRUCK Gm 5.3l 6.0l 6.2l Ls Gen Iv 58x Tooth Crankshaft Oem fits 303 2010
The **Chevrolet 303.GM8X10 5.3L, 6.0L, and 6.2L LS Gen IV 58x Crankshaft (Part Number: 125521185809)** is a precision-engineered component designed to deliver exceptional performance and reliability in General Motors iconic LS-series V8 engines, spanning the 5.3L, 6.0L, and 6.2L displacements. This crankshaft is a critical part of the **Gen IV LS platform**, which has become legendary for its durability, high-revving capability, and broad application across Chevrolet, GMC, Cadillac, and other GM performance and muscle car models. Crafted from high-grade **forged steel**, this crankshaft features a **58mm journal diameter**, a dimension carefully optimized to balance strength, smooth operation, and compatibility with aftermarket and factory-built engines. The **GM8X10** designation indicates its specific design iteration, tailored to meet the demands of both stock and modified applications, including high-performance builds, drag racing, and street rod projects. With **five main bearing journals** and **seven counterweights**, this crankshaft ensures balanced rotational inertia, reducing vibration and enhancing engine longevity even under extreme loads. The **5.3L, 6.0L, and 6.2L compatibility** makes it a versatile choice for restomod enthusiasts, allowing for easy swaps into engines like the **L96 (6.2L), LQ9 (6.0L), and LFP (5.3L)**, as well as aftermarket builds using LS-based blocks. Whether paired with a **stock rod, a custom big-block setup, or a high-performance camshaft**, this crankshaft delivers the structural integrity and precision machining required to handle aggressive power outputs while maintaining reliability. Built to GM s exacting standards, it features **precision-ground journals** and **laser-machined surfaces** for optimal oil flow and reduced friction, ensuring smooth operation across the engine s rev range. For builders seeking a balance of strength, compatibility, and performance, the **125521185809 GM8X10 crankshaft** is an indispensable upgrade, capable of supporting everything from mild street engines to extreme power applications without compromising durability.
### **Pros and Cons of Buying a Chevrolet 303 (GM 8x10 GM 5.3L/6.0L/6.2L LS Gen IV 58x Crankshaft Part Number 125521185809)**
The **GM 8x10 crankshaft (part #125521185809)** is a critical component for **LS-based engines (5.3L, 6.0L, and 6.2L)** in vehicles like the Chevrolet 303 (a performance-oriented truck or SUV). Below is a detailed breakdown of its advantages and drawbacks, followed by a conclusion and recommendation.
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### **Pros of the GM 8x10 Crankshaft (125521185809)**
1. **Improved Strength and Durability**
- The **8x10 crankshaft** is a **forged steel** design with **larger main journals (8mm) and rod journals (10mm)** compared to the stock **7x9 crank**, increasing structural integrity.
- Better suited for **high-performance builds**, **forced induction (turbo/supercharger)**, and **high-RPM applications** without excessive stress.
- Reduces the risk of **crankshaft failure** under extreme loads, which is common in **big-block-style builds** or **high-torque applications**.
2. **Better Compatibility with LS Gen IV Engines**
- Designed to work with **LS3, LS7, and LS9 engines**, as well as **aftermarket LS swaps** (e.g., in muscle cars, trucks, or marine applications).
- Fits **5.3L, 6.0L, and 6.2L LS engines** with minor or no modifications (depending on the specific engine configuration).
- Often used in **LS-based supercharged/turbocharged builds** (e.g., **LS3 with a supercharger**) where stock cranks may fail.
3. **Supports Higher Horsepower and Torque**
- The **larger journals** allow for **better oil film thickness**, reducing wear in high-performance applications.
- Can handle **forced induction setups** (e.g., **turbocharged LS3 making 800 HP**) where stock cranks would likely fail.
- Used in **race engines** and **high-revving applications** (e.g., **LS swaps in drag cars**).
4. **Aftermarket Support and Availability**
- Widely available from **GM dealers, performance shops, and online retailers** (e.g., **Jegs, Summit Racing, eBay**).
- Many **aftermarket engine builders** recommend it for **LS-based powerplants** pushing **500 HP**.
- Often paired with **LS Gen IV rods, pistons, and connecting rods** for a complete high-performance setup.
5. **Reduces Risk of Catastrophic Failure**
- Unlike stock cranks, which can **twist or break** under extreme stress, the **8x10 crank** is **less prone to failure** in high-load scenarios.
- Used in **LS-based marine engines** and **truck powerhouses**, proving its reliability in demanding conditions.
6. **Retains LS Gen IV Benefits**
- Still benefits from **LS Gen IV s** **hydrodynamic main bearing caps, balanced crankshaft, and modern machining**.
- Works seamlessly with **LS oil pumps, timing chains, and rod bearings** designed for the platform.
---
### **Cons of the GM 8x10 Crankshaft (125521185809)**
1. **Higher Cost Than Stock**
- **Significantly more expensive** than an **OEM LS Gen IV crank** (stock 7x9 cranks are cheaper but weaker).
- Pricing typically ranges from **$1,200 $2,500 **, depending on source and whether it s **new or used**.
- Requires a **budget for a full engine rebuild** if installing it in a stock engine.
2. **Not Necessary for Mild Builds**
- If the engine is **naturally aspirated and making under 400 HP**, a **stock crank may suffice** without needing an upgrade.
- Overkill for **daily drivers, mild turbocharged setups (under 500 HP), or stock LS3 builds** unless pushing for **extreme power**.
3. **Requires Supporting Modifications**
- Installing an **8x10 crank** often means upgrading **connecting rods, pistons, and bearings** to match its strength.
- May require **custom machining** (e.g., **rod length adjustments, main cap modifications**) for a perfect fit.
- Some **aftermarket rod kits** (e.g., **Scat, JE, or ARP**) are needed to complement the crank.
4. **Potential for Compatibility Issues**
- **Not all LS engines are drop-in compatible** some may need **custom spacers, timing chain adjustments, or rod length changes**.
- **LS3/LS7 engines** may require **different rod lengths** to clear the crank s larger journals.
- **Marine or truck applications** may need **additional seals, mounts, or cooling modifications**.
5. **Weight Consideration**
- **Forged steel cranks are heavier** than cast iron stock cranks, which can slightly affect **engine balance and vibration**.
- While negligible in most cases, **race engines** may require **additional balancing** for high-RPM applications.
6. **Installation Complexity**
- Replacing a crank requires a **full engine teardown**, which is **labor-intensive and costly**.
- If not installed correctly, it can lead to **oil leaks, bearing failure, or premature wear**.
- **Not a simple "drop-in" replacement** requires **proper machining, gasket replacement, and torque specifications**.
7. **Limited Longevity Without Full Engine Support**
- If the rest of the engine (e.g., **stock pistons, rods, or bearings**) is not upgraded, the **8x10 crank may still fail** under extreme stress.
- **Must be paired with a full high-performance kit** (e.g., **Scat rods, ARP bolts, forged pistons**) for true reliability.
---
### **Conclusion**
The **GM 8x10 crankshaft (125521185809)** is a **premium upgrade** for **LS-based engines** pushing **high horsepower, forced induction, or extreme torque**. It is **ideal for:**
- **Turbocharged/LS3 builds making 600 HP**
- **Supercharged LS engines (e.g., LS3 with a supercharger)**
- **Race engines, marine applications, or truck powerhouses**
- **LS swaps in muscle cars or high-performance trucks**
However, it is **not necessary** for:- **Stock or mildly modified LS engines (under 400 HP)**
- **Budget builds where cost is a major concern**
- **Engines that will never see extreme loads**
If you are **building a high-performance LS engine**, the **8x10 crank is a wise investment** but it must be **paired with the right rods, pistons, and bearings** to avoid failure. For **stock or mild builds**, a **stock crank may be sufficient**.
---
### **Final Recommendation**
- **Buy the GM 8x10 crankshaft (125521185809) if:**- You are **building a turbocharged or supercharged LS engine** (500 HP).
- You are **swapping an LS engine into a high-stress application** (e.g., **truck, marine, or race car**).
- You plan to **run extreme torque or high RPMs** and want **maximum durability**.
- You are **already upgrading rods, pistons, and bearings** for a full high-performance build.
- **Avoid it if:**- You are on a **tight budget** and only need **mild power gains**.
- Your engine will **never exceed 400 500 HP** naturally aspirated.
- You are **not prepared for a full engine rebuild** (crank replacement is not a simple swap).
**Best Practice:**- **Get it from a reputable supplier** (e.g., **GM Performance Parts, Summit Racing, or a trusted engine builder**).
- **Pair it with a full high-performance kit** (e.g., **Scat rods, ARP bolts, forged pistons**).
- **Have a professional install it** to ensure proper machining and assembly.
- **Consider a used but high-quality crank** if budget is a concern (check for **cracks, wear, or machining quality**).
For most **serious LS builders**, the **8x10 crank is a worthwhile upgrade** but it should be part of a **comprehensive engine upgrade**, not a standalone fix.
Details:
Some items do have more wear than others.
part #: 303.gm8x10 prices
- $189.95-$200.00
specifications cranshafengin:
- for makes: Chevrolet
- for years: 2010
- brand: Chevrolet Truck
- part type: Crankshaft
- conditions options: 5.3l 6.0l 6.2l 58x Crank
- genuine oem: Yes
- ipn: 303.gm8x10
shipping cranshafengin:
- carrier: FedEx
- transit: 2-5 Days
- type: Fixed
- class: Standard
- cost: $60.00
- service: FedEx Ground / FedEx Home Delivery
returns cranshafengin:
- paid by: Buyer
- policy: Returns Accepted
- time: 30 Days
offer cranshafengin:
- best offers: True
- started: April 15, 2026
- options: Ship-to-home
- sold: 0
- quantity: 1
- availability: In Stock
seller cranshafengin:
- # reviews: 16141
- rating: 99.6%
- city: Easley, South Carolina
general cranshafengin:
- Car Truck Parts Accessories > Engines Engine Parts > Crankshafts
- condition: Used
payments cranshafengin:
- credit card: Mastercard
- other
- wallet: Google-pay
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