Allison 1000/2000/2400 6-Speed Overhaul Rebuild Kit 06-Up

Allison switched the 1000/2000/2400 from a five-speed to a six-speed for the 2006 model year, right when GM moved to the LBZ Duramax, so a kit that says "06-up" is cut for the later six-speed valve body and clutch stack - do not use it on the earlier five-speed units. This is the overhaul package you reach for when a high-mile Duramax truck starts slipping in the C3 clutch range, bangs into gear, flares on the 3-4 shift, or shows burnt fluid after a hot tow season.

It fits the 2006-and-later Allison behind the 6.6L Duramax - Chevrolet Silverado and GMC Sierra 2500HD and 3500HD, plus the Kodiak and TopKick and other medium-duty trucks running the LT1000, LT2000, or LT2400. In the box are the friction and steel clutch plates, the full overhaul gasket set, and the complete rubber seal and O-ring set - the soft parts and clutches that wear out on a teardown.

On the bench this is what goes back in after you strip the unit, clean it, and inspect the drums, pistons, and pump: replace every friction and steel, reseal the pistons and accumulators, and lay in fresh gaskets and seals before the case and control valve body go back together. Soak the new frictions in clean ATF before assembly and check your clutch clearances as you stack each pack so it shifts firm and holds under load.

This is a soft-parts-and-clutch overhaul kit: it does not include hard parts, the pump, the torque converter, or a filter, so reuse or replace those separately based on what your teardown shows. Ships from the USA; handling in 1-2 business days.