Allison 1000 Transmission Filter and Pan Gasket Kit, Duramax

An internal transmission filter and matching pan gasket for the Allison 1000 (LCT1000) six-speed in 2001-2019 Chevrolet and GMC 2500 and 3500 trucks with the 6.6L Duramax. It is built for the standard-depth factory pan and interchanges with AC Delco 29542833. Everything needed for the pan side of a fluid service is in the box.

On these trucks the internal filter is the one that gets skipped. Most owners change the external spin-on lube filter and do a drain-and-fill, but the pickup filter in the pan keeps loading up with clutch material and wear metal. Once it restricts, the pump starves under load, line pressure drops, and you start seeing slipping, flare on the 1-2 or 2-3 shift, and higher fluid temps when towing. A restricted filter also shows up as a whine that changes with engine speed.

Service is straightforward: drain the pan (15 mm drain plug), remove the pan bolts (13 mm), and pull the old filter straight down out of the pump inlet. Check the old filter neck seal did not stay behind in the case bore, clean the pan and the magnet, push the new filter fully home, and set the pan with the new gasket. Torque the pan bolts evenly in a cross pattern to factory spec and refill with the correct Allison-approved fluid. Plan on changing the external spin-on filter at the same time so both circuits start clean.

Change interval is typically 25,000-50,000 miles depending on use, sooner on trucks that tow heavy or run hot. Always confirm pan depth before ordering: trucks with the deep or aftermarket pan take a different filter.