Allison 1000 Transmission Repair and Rebuild Manual

This is the ATSG TechTran technical manual for the Allison 1000 and 2000 Series, the five- and six-speed automatic that sits behind the 6.6L Duramax in GM 2500HD and 3500HD trucks and behind medium-duty gas and diesel engines in C-Series and K-Series chassis from 2000 up. It is a Generation 1 unit book, so it carries the early five-speed material along with the later six-speed changes and the LCT1000, LCT2000 and 2400 variants that share the same case family.

Content is the working material: principles of operation for each range, the clutch apply chart, exploded views and component identification, disassembly and reassembly order, and the full electronic side of the unit. That electronic section is the reason most people buy this book. It has valve body identification, internal wiring harness routing and locations, TCM and solenoid electrical diagrams, and the diagnostic charts you need when the truck sets a solenoid or clutch slip code. Torque values and clearance data are included for buildup.

On the bench the normal sequence is to confirm the unit and valve body version first, since the 1000 changed internally more than once, then work the clutch apply chart against the symptom before splitting the case. C1 and C2 clutch failures, sticking shift valves and internal harness chafe all read differently once you can map the complaint to an apply circuit. Coming back together, the shim and selective spacer sections keep the clutch pack clearances honest, which is where most warm-up shift complaints come from on a rebuilt 1000.

Printed shop manual, spiral-flat format, roughly 11 by 8.3 inches. No subscription, no laptop, no login. It lives on the bench and takes ATF fingerprints like it should.