1st any swap MUST meet the epa stuff (smog etc) for the year of manufacture. You cant stuff a GMC 4-71 under there as that is NOT electronic direct injected - required from 2009 on. SO you are limited to EDI and that limits you even further - maybe fiat has a diesel approved for USA. Not sure.
There are conversions available from Bruiser - Cummins 3.9L 4BT for 07-11, Cummins 3.9 ISB (common rail) for 07-Current or the 3.8L ISF 11-current - shoot them an email and inquire as to cost before you spend a lot of grey matter and time researching the low end alternatives...
80-100 hrs labor (6000). Plus engine (5000new) plus conversion kit (1000) plus small parts.
So I would guess 7-12K depending on engine (used or new)
AND - mounts to sump is deeper on the cummins - you will need at least 4" lift to clear oil pan at axle - and will not have a whole lot of uptravel... another 4K.
So unless your budget is 10-15K why pipe dream?
Of course you've already spent that on oil this year right?
J Wm Bishop EA, ASADE
Classy Chassis Customs. Because the only thing that matters is what's UNDER the dress ...