Rear Block Off Plate - GM Powerglide

The Rear Block Off Plate for GM Powerglide by COAN is an essential sealing component designed for builders and mechanics working with Powerglide automatic transmissions in high-performance and street applications. This precision-engineered plate blocks off the rear extension housing opening, preventing fluid leakage and maintaining transmission integrity when the stock tailshaft is removed or replaced with custom driveline components. Whether you're upgrading to a shorter tailhousing, installing a custom yoke, or converting to a different driveshaft configuration, this block off plate ensures a clean, leak-free seal.

Built to OEM specifications, the Rear Block Off Plate features precise engineering that matches GM Powerglide housing dimensions, ensuring proper fitment and sealing without gaps or misalignment. The compact 5.25 x 5.35 inch profile and minimal 0.18 lb weight make installation straightforward without adding unnecessary bulk to your transmission assembly. Its durable construction withstands the heat and pressure cycles of transmission operation, whether in street-driven vehicles, bracket racing setups, or vintage hot rods where Powerglide transmissions remain a popular choice for their reliability and compact footprint.

This block off plate is ideal for restorers, drag racing enthusiasts, and transmission shops fabricating custom driveline solutions for GM-powered vehicles. Installation requires access to the rear transmission housing and basic mechanical knowledge; the plate seals against the housing surface to prevent ATF weeping during operation. Compatible exclusively with GM Powerglide three-speed automatic transmissions, it pairs seamlessly with aftermarket tailhousing kits, custom adapter plates, and shortened driveshaft assemblies, making it a critical component for any serious Powerglide build where OEM-quality sealing is non-negotiable.