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Call or Text (352) 722-5295What the Allison parts shelf covers on an LMM Silverado
The parts side of this transmission sorts into a short list: torque converters, flex plates, valve body and calibration parts, cooler lines and coolers, pans, filters and fluid, and PTO covers. That mirrors how the six-speed is serviced. Fluid is Dexron-VI, the 2006-2010 sump filter is the TF920 and the spin-on is the TF950, also sold as Allison 29539579, on a 50,000 mile normal or 25,000 mile severe interval. The Silverado HD came with an auxiliary external heavy-duty transmission oil cooler from the factory, so added cooling here is a capacity increase rather than something the truck never had.
What wears and what breaks
The cooler lines are the standout. They leak at the crimped hose-to-hardline joint, sometimes under 25,000 miles, and the result is red ATF misted on the frame and crossmember, rising temperature and flare shifts. The torque converter is the power-sensitive part: the stator cracks and the front cover balloons, then the debris circulates. With age the valve body valves can seize in worn bores, pump gears lose efficiency and babbitt bushings wear, which shows up as sloppier shifts, quick downshifts under load and delayed engagement. Slipping in the C3 gears and limp mode locked in third tend to follow added power or heavy towing.
Maintenance parts vs. strength parts
Split your list in two. Maintenance is fluid, filters, pan gaskets, reseal kits and cooler lines, and on a truck that tows it is worth doing early and often; some heavy towers run intervals far shorter than the book. Strength parts are the ones that change what the transmission can take: a billet C2 hub, a billet P2 planetary, a PTO cover that routes oil to the C3 clutches, hardened pump gears, bronze bushings and genuine Allison solenoids, plus a billet-cover multi-disc converter and valve body work once TCM calibration is done.
What we carry
PPE covers most of the hard parts: billet input, intermediate and output shafts, a billet C-2 clutch hub, C5 clutch and Stage 5 and Stage 6G kits, valve body recalibration and pressure calibration kits, deep and low-profile pans with matching deep-pan filters, pan gaskets, bar-and-plate coolers, a transfer case brace and PTO side plate covers. Merchant Automotive has the converter housing reseal kit and pass-through connector seal, BD Diesel the six-speed valve bodies and cooler and filter kits, and ATS Diesel Performance and Fleece Performance Engineering more transmission hard parts. Allison Transmission supplies the deep pan, spin-on filter and PTO cover gasket; Mishimoto pans and fluid coolers; XDP flex plates and a direct-fit oil cooler; Mag-Hytec deep sump pans; Hot Shot's Secret fluids and additives; Dorman converter bolts; and ACDelco the transfer case output shaft seal.
Fitment notes
Filter depth has to match the sump, so a deep pan needs its deep-pan filter and a stock pan needs the standard one. Valve bodies and shift kits for the 2006-2010 six-speed are listed apart from 2011-and-up parts, and the shift kit was 2006-2008 only. Keep off 2011 listings in general, since that year brought the LML and a different driveline. Verify by VIN or use the fitment checker on the product page.
Frequently asked questions
What fluid and filter does the Allison 1000 take?
Dexron-VI, nothing else. The 2006-2010 internal sump filter is the TF920 and the spin-on is the TF950, also cataloged as Allison 29539579. Published service is 50,000 miles for normal use and 25,000 for severe duty, and trucks that tow heavy are often serviced more often than that.
Do I need a different filter with a deep pan?
Yes. Internal filter depth differs between a deep sump and the standard sump, and running the short filter in a deep pan leaves the pickup too far from the fluid. Buy the filter that is listed for the pan you are installing, and replace the pan gasket at the same time.
What does the PTO cover upgrade actually do?
An aftermarket PTO cover routes oil to the C3 clutches, which is the pack owners report slipping once power or towing load goes up. It is one of the proven internal upgrades on this transmission, along with a billet C2 hub, billet P2 planetary, hardened pump gears, bronze bushings and genuine Allison solenoids. It is a worthwhile add any time the transmission is already open.
Not sure what fits? Call the shop at the number in the header, or use the fitment checker on any product page. We install everything we sell.