Description
Product Overview
The Frianchly rear main gasket is a direct replacement for part number BS40640, designed specifically for Chevrolet and GMC vehicles equipped with 4.8L, 5.3L, and 6.0L LS2/LS3 engines. Constructed from a high‑temperature resistant composite, the gasket offers superior sealing capability under extreme pressure and heat. Its precision‑cut dimensions ensure an exact fit, eliminating the need for modifications and guaranteeing a leak‑free seal that protects engine oil pressure and performance.
Usage
This gasket is ideal for both professional repair shops and DIY mechanics performing rear main seal replacements during engine rebuilds, overhauls, or routine maintenance. It fits seamlessly into the engine block, providing a reliable barrier that prevents oil leakage and maintains optimal lubrication. 
Why Choose Us
Frianchly adheres to strict quality standards, employing advanced manufacturing techniques to produce consistent, high‑precision components. Each gasket undergoes rigorous testing for dimensional accuracy, material integrity, and durability. Our commitment to reliable service includes a responsive support team ready to address any concerns, ensuring customer satisfaction and confidence in every purchase.
Key Features
- Exact OEM fit for Chevy and GMC LS2/LS3 engines
- High‑temperature composite material resists wear and deformation
- Precision‑cut design eliminates installation guesswork
- Provides a leak‑free seal to protect engine oil pressure
- Easy installation with standard tools, reducing labor time
FAQ
Does this gasket fit a 5.3L LS engine?
Yes, the gasket is compatible with 5.3L LS engines found in many Chevrolet and GMC models.
What is the recommended torque for the rear main seal bolts?
We recommend tightening the bolts to the manufacturer’s specification, typically around 30‑35 ft‑lb, using a calibrated torque wrench.
Can I install this gasket myself?
Absolutely. The gasket is designed for straightforward installation with standard tools, and our installation guide provides step‑by‑step instructions.
Is there a warranty on this product?
Frianchly offers a one‑year limited warranty covering manufacturing defects. Contact our support team for assistance.
What should I do if I experience an oil leak after installation?
First, verify that the gasket is seated correctly and that all bolts are torqued to spec. If the leak persists, contact our customer service for a replacement or further troubleshooting.





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