New ATSG service manual for the 1964-1991 TH400 automatic transmission

This transmission is known by a few different names including:

TH400, TH-400, 3L80, TH475, THM375, M40, THM400, THM-400, 3L80HD, ST400, ST-400 Turbo-Hydramatic

This is the book that all the shops use. If you have plans to rebuild your transmission yourself, I would highly recommend this manual. It's extremely easy to follow and has great illustrations. 

Check out our eBay store for great deals on torque converters and other transmission parts.