kinda depends on your set up Lifted? street or trail?
If you need drive shaft clearance, then a T 350 is a good idea. If you drive it on the hi way, I'd go for a 700r4, that is if you have enough gearing, if not the 700r4 will cycle back and forth in and out of OD. If you want stronger, then the T400 is as hearty as you can get for that year.
thanks for the info yes it is lifted with a 12 inch lift and i am mostly using this truck as a street truck but want a tuff tranny that will hold up to the big tires
The tire size is an issue, but your gearing is more of an issue.With 12 of lift, I think I would go with the T350, smaller pan and easier to clear front drive shaft.