i know one person who swears by them and has a 1986 custom 12v SWB chevy dually and a '94 chevy with a 4BT and has built several others. it is a time consuming and costly swap but if you plan on towing its great. same goes if being different is your goal.
what i personaly know:
you can use the TH400, 700R4/4L60 with an adaptor
cummins' own hardcore
you will need to buy or fab motor mounts, and ive heard, use one ton springs in the front to account for the added weight of the cummins
there are a few forums on the interweb dealing with cummins' and such swaps, join one, there are allot like you in that aspect. you will find haters though...[duramax guys] just kidding about the last part
what i personaly know:
you can use the TH400, 700R4/4L60 with an adaptor
cummins' own hardcore
you will need to buy or fab motor mounts, and ive heard, use one ton springs in the front to account for the added weight of the cummins
there are a few forums on the interweb dealing with cummins' and such swaps, join one, there are allot like you in that aspect. you will find haters though...[duramax guys] just kidding about the last part