10L1000 Cast Aluminum Deep Transmission Pan Kit 128051400

This is a cast aluminum deep transmission pan for the GM 10L1000 ten-speed automatic that sits behind the 6.6L Duramax diesel in 2020-2026 Chevrolet Silverado 2500HD and 3500HD and GMC Sierra 2500HD and 3500HD trucks. It is sold as a replacement for pan part numbers 128051400, 840171200300 and 24286058. It fits the diesel 10L1000 only. Gas heavy-duty trucks use a different transmission and pan, so check your build sheet before you order.

The kit comes with the pan, a pan gasket, a transmission filter, 16 M6 mounting bolts with washers, a hex key and a pair of shop gloves. The pan has a drain plug and a finned, ribbed body with internal baffles. It sits deeper than the stock pan, so it holds more fluid and gives heat more surface to leave through. That matters on a truck that tows heavy or runs a plow, where fluid temperature is what kills clutches and solenoids.

To install it, drain the fluid, drop the factory pan and pull the old filter straight down. Clean the case sealing surface without gouging it, set the new filter, then hang the pan with the new gasket. Snug the bolts by hand, then torque them in a crisscross pattern to the factory spec so the flange pulls down evenly. Refill with the fluid GM specifies for the 10L1000, then check the level hot with the engine running using the factory procedure. A deeper pan takes more fluid than the stock fill, so do not go by the old refill number.

A deep pan also makes the next service easier. The drain plug lets you change fluid without dropping the pan, and any clutch material or metal will show up on the plug and in the bottom of the sump when you do.