The 700 is a great transmission, however, it may be a bit light for a 1 ton truck that's still getting used as a truck. GM didn't use them in anything bigger than the light duty 3/4 ton. There is another option, though; The 4L80E. That one is more or less a TH400 with an overdrive. It was used in 3/4 ton HD models, as well as 1 ton trucks. If you don't mind doing the setup for the PCM, you may consider looking for a decent used 6.2/4L80 combo from a late model truck. Just make sure to get everything that goes with it.
