Allison 1000 Deep Transmission Pan Kit with Filters

This is the complete Allison deep pan conversion for the 1000 Series: the genuine Allison deep sump pan (29536522), the matching internal deep filter (29542824), and the external spin-on filter (29539579). The deep pan adds roughly three quarts of fluid capacity over the factory shallow pan, which is the single cheapest thing you can do to drop fluid temperature on a truck that tows.

Fits Allison 1000 Series (and 2000 Series sharing the same pan rail) from 2001 to present, behind the 6.6L Duramax in Silverado and Sierra 2500HD/3500HD as well as GM medium-duty chassis. Because the internal filter sits lower in a deep pan, you must run the deep filter (29542824) with this pan - a shallow filter will leave the pickup above the fluid line and aerate on hard pulls. Both filters are included here so you are not hunting part numbers at the counter.

On the bench or on the lift: drop the factory pan, pull the old internal filter straight down off the pump pickup, seat the new deep filter fully until the neck bottoms out, then hang the deep pan. The pan gasket is reusable and is not included, so inspect the one on your truck and reuse it if the bead is intact. Fill roughly three quarts over your normal service fill, run it up to temperature, and set the level on the hot check. Spin the new external filter on last and prime it.

The failure this solves is heat. A stock shallow pan on a loaded 2500HD will run fluid well past 220F on a grade, and Allison fluid that lives above 220F cooks the clutch material and varnishes the valve body. More fluid volume means more thermal mass and a lower steady-state temperature, and the deeper sump keeps the pickup submerged when the truck is nose-up on a ramp or a trailer tongue is loading the rear.