The quickest , most economical way to get what you want is to find a early '90's K2500 or K3500. The 93-94 NV4500 had the lower first gear. You'll get all the components you need:350 engine,5spd trans w/crossmember,transfercase,axles,bellhousing w/hyd clutch, plus much more. You can swap out to a carb/intake & non-computer HEI distributor. I see whole trucks all the time for less than $2k. Try finding half these items separately for that.
I forgot, some of the one tons had 454's & single rear wheel.
The '90s K trucks were ifs, so the axles would not be compatible. What you would need would be a V series 4x4 ('81-'87 body), but they did not come with the 5 speed, those were used on the GMT400 and up chassis only.
