Uncle Wally,
If you don't yet have the engine yet, get the 24v. I'm not certain what the hp rating (220ish??)is but it is awesome as diesels go. I had the '98 12v and test drove the '98 24v once. I want one so bad... but the funds aren't there yet.
I'b be concerned about the weight of the cummins, 1000 or 1100 lbs.
I have no idea if the trans you've selected will hold up or not I'd bet it will.
Keep us informed
DChristie
\'04 DA Silverado 4x4 quadcab 143k, New injectors, 4" exhaust (love the tone!!) Edge evo CTS, KD megafilter and liftpump.