Genuine Allison 29536522 deep sump pan for Allison 1000 Series transmissions, adding about three quarts of fluid to run cooler while towing.
Every Duramax generation that came with the Allison 1000, from the 2001 LB7 through the LLY, LBZ, LMM, LML and the 2017-2019 L5P, left the factory with a shallow stamped transmission pan. That pan hangs low enough to get dented on rocks and trailer ramps, it rusts at the rail on salt-belt trucks, and it holds the smallest fluid volume Allison offers for the 1000 Series. This listing is Allison part 29536522, the factory deep sump pan, for owners replacing a damaged or weeping pan who want to come out of the job with more fluid capacity than they started with.
Heat is the main thing that wears out an Allison 1000 in a working truck. The clutch packs, seals and the torque converter clutch all live in the fluid, and that fluid only sheds heat when it passes through the cooler. Between trips, the sump is the heat sink. Allison's bulletin on fluid and filter changes gives the refill volume for the shallow sump at about 7.4 quarts and the standard sump at about 10.6 quarts. This pan is the standard-depth sump, so the same truck carries roughly three more quarts and its fluid temperature climbs more slowly on a long pull. The deeper floor also keeps the filter inlet submerged during hard braking, steep launches and off-camber driving.
Drain into a clean container and look at what you get. Normal fluid and a filter with only fine sludge mean the transmission is healthy and the pan swap is a good upgrade. Chunks of friction material, a lot of metal, or a truck that slips at normal temperature point to clutch or valve body trouble, and a bigger pan will not change that. The Allison 1000 service guide walks through a normal service, and if the truck has been throwing codes or dropping into a fixed gear, read the limp mode causes guide first.
The pan fits Allison 1000 Series transmissions. In GM pickups that is the 2001-2019 Chevrolet Silverado and GMC Sierra 2500HD and 3500HD with the 6.6L Duramax (and the 8.1L gas engine), along with Allison 1000 medium-duty chassis. It does not fit 2020 and later HD pickups, which use the 10L1000. Pan bolt patterns are shared across the 1000 Series, but if your truck has an aftermarket pan or you are unsure what transmission is in it, send us your year and VIN before ordering. Related parts are grouped in the Allison 1000 collection.
The pan is stamped steel with a machined sealing surface, weighs about 8 lb, and uses the stock bolt pattern.
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Doing this repair right usually means replacing these at the same time. Same transmission, ships together.
Any Duramax truck with the Allison 1000: the LB7, LLY, LBZ, LMM, LML and the 2017-2019 L5P in Silverado and Sierra 2500HD/3500HD. It does not fit 2020 and later trucks with the 10L1000.
The deep suction filter, Allison 29542824. The shallow filters (29542833 and 29537965) are too short for a deep pan and will draw air.
Allison lists about 10.6 quarts on a refill for the standard sump versus about 7.4 for the shallow sump, so plan on roughly three quarts more than a normal service. Set the final level on the dipstick hot.
Only if it is undamaged. A gasket that is cut, flattened or was leaking should be replaced. The deep pan filter kit includes a new one.
Only if the slip comes from the filter uncovering on steep launches. A transmission that slips at normal temperature on level ground has worn clutches or a valve body problem and needs diagnosis.
