Dakota/Durango drivetrain in an Abody?

sory if im reposting couldnt find the info i was looking for. Ive gotten hints here and there about using 90's-04 Daks and Durangos in a bodys. stuff like the tranny and rear end. what are the complications with this? I kno they use 8.25 rears that are 29 spline instead of 27(?) but do they need to be cut down to fit? and what about using a tranny with overdrive? are there electronics i need to play with? Cuz if thats the case ill stick with a 904!