Ford Truck Enthusiasts Forums - Cummins Conversion

best trans option is impossible to answer....

there's cheapest, easiest, most functional, most dependable, or best of all worlds (except price tag)

-getrag 5 speed or nv4500 mated to a cummins donor would be the cheapest and probably the easiest. need to use a dodge tcase.

-zf5 is probably the most abundant trans to find and is every bit as stout as the getrag and nv, if not more stout (except for the trans mount breaking....but that's easily fixable) and has far serviceability than the dodge tranny's.

-a ford zf6 is the strongest of the pickup transmissions, and is probably the strongest of any pickup ever. very reasonably priced both to buy and to service. need an expensive trans adapter.

-nv5600 is very stout, hard to find, not very serviceable, very expensive, but you wont need an expensive trans adapter. this is the easiest 6 speed to use in older vehicles because its the only one that can fit inside trans tunnels. the trans itself is long and short vs the other 6 speeds which are giants in the height department with not as much length.

-g56 expensive, not as reliable or stout as nv56 or zf6, but still very stout and capable. no adapter required.

I cant help ya with automagics. pretty much any of the 4 speed electronic transmissions can easily work with standalone controllers. but I don't know why anyone would want that. . . .

-you could run your c6 with a gear vendor. c6 very stout, cheap, you already have one, built ones are cheap, but torque converter selection is limited to old technology.

so the answer is impossible. too many variables. those are common options, I hate automatics and as far as manuals go, I cant stand the gear spread of a 5 speed. its 3 useable acceleration gears.....at least a 6 spd gives you 4.