[mrein3]

Advanced adapters makes an output shaft for a 700r4 transmission that will work with the th350 adapter you already have. I personally haven't done the swap yet but the tranny core is laying on the floor of my shop right now.

You take a core 700r4 and the output shaft to a good rebuilder and tell him what you want.

Back on the truck you need to consider two options. The 700r4 is just shy of two inches longer than your th350. You can either leave the engine where it is and move the trans/adapter/t-case back or leave the trans/adapter/t-case where it is and move the engine forward.

Moving the trans back forces you to have your drive shafts shortened in the back and lengthened in the front. Moving the engine keeps all your drive line stock but forces you to deal with the fan sticking too far into the fan shroud. There is enough room to go forward. An electric fan set-up would over come any cooling problems.