hello, my dad has a 03 ext cab short bed 4x4 and i was wondering if i were to find a allison 2k or 3k model would it bolt up the same and would i need a different computer? would the transfer case bolt up the same? and would the driveshaft need adjusted? thanks in advance for any help to my answers

 

theyre not a direct fit, an th 2k and 3k are huge

 

Yeah. Those transmissions have heavy internals...probably more adept to pulling huge loads than spinning up really fast.