Allison 1000 Deep Transmission Pan for Duramax

This is the genuine Allison Transmission deep-sump oil pan, part number 29536522, for the Allison 1000 Series automatic behind the 6.6L Duramax diesel in GM trucks. It is a direct-fit upgrade over the shallow factory pan on 2001-2019 Chevrolet Silverado and GMC Sierra 2500HD and 3500HD, and it also fits the related 2000 and 2400 Series units. It drops the sump roughly one inch and holds about three extra quarts of ATF.

On a truck that tows or hauls, fluid temperature is what kills an Allison. The clutches and the TCC cook when the fluid gets hot and stays hot, and a bigger charge of oil is the cheapest way to buy back some margin. The larger, deeper sump carries more fluid to move heat away from the clutch packs, and the extra depth also puts the drain plug and filter down away from aerated fluid so the pump keeps a solid pickup on grades. It is a common first upgrade on a Duramax that sees a trailer.

Plan it as a full service. The deeper pan requires the matching deep-pan internal filter (29542824) plus a fresh spin-on filter (29539579) and a new pan gasket; the shallow-pan filter will not reach. Clean the sealing surface, set the filter, hang the pan and torque the bolts in a cross pattern to Allison spec, then fill with the correct Dexron-VI type fluid, run it up to temperature, and set the level per the sight-glass or fill procedure for your year. Stamped steel, built to Allison factory specification. Ships from the USA; handling in 1-2 business days.