I recently picked up an 03 Ram with a blown up Hemi in it and was thinking of swapping my 12 Valve out of my rusty old 94. Was wondering if anyone who had done the swap could give me a few pointers on what I would need motor mount wise and what I would need from a Common Rail or use from the Hemi?

 

Motor position will be different. Is the '03 2WD or 4WD? You will have to re do the motor mounts, but that's the biggest difference/hardest part. Obviously you will need a trans, because the trans that bolts up to the Hemi, will not work behind the Cummins. Also change out fuel pump/lift pump. On the Hemi, pump will be in tank. That pump puts out @ 50+ PSI, and the lift pump in the 12 valve (and all Cummins for that matter), are low pressure pumps. Not to mention, you would need to change out fuel lines anyways...from fuel tank to lift pump.
But getting the actual 12 valve up and running, would be the easy part.

Radiator/fan/fan shroud will all be different as well. Not sure why you mentioned Common Rail. From what I read, you have a '03 Gas motor 2500, and wanting to drop in a 12 valve motor in it. So...where does Common Rail fit in?

 

It is 4WD. I decided I'm going to look for an NV4500 to hopefully save a little bit of trouble. And the Common Rail fits in because I read on a few other threads here and there they used some parts off a CR to get some things working. And I was thinking for the radiator, fan, IC, and all that using CR parts would for the most part be basically usable. Might just need some piping.