Re: TH400 3 speed autos Guess I am going to go against the grain here, but that 3 speed auto used in the M1008 military trucks equiped with the 6.2 is the TH400, one of the best and most heavy duty automatic transmissions ever built. They have been used in light and medium GM, AM General and Volvo trucks, heavy GM cars like the Olds, Pontiac and Cadillac, as well as Ferrari and even Rolls Royce. As pointed out by Carey, the 4L80E is a later OD version of the TH400. If you want your 4x4 auto trans to live long, the TH400 or 4L80e is the right choice. By contrast, the 700r4 is an overdrive version of the TH350, a much lighter weight auto trans not designed for heavier vehicles. True, GM did put the 700r4 behind 350s in Suburbans, but I continue to marvel at how many smoked 700r4s I've seen in those vehicles - they do not stand up.