v-6 in early A-body
I would drive a Chebby before I put a 4.0 in anything Mopar, I have spent the last 18 years taking 4.0's OUT of vehicles for the very same reason I would not put one in....its a tractor engine designed in the 50's that makes poor power, crappy MPG and has no top end. Same for diesel, in a heavy vehicle they might be tolerable but in a light car the power is all wrong, both are done making power at 3K and you certainly dont need to move torque curve low enough to spin tires at 1200 rpm but run out of revs before the top of the on ramp. Freeway driving kills either of those engines and without overdrive both would be miserable. Ever drive a Jeep 4.0 on freeway? There is a reason why my Jeep Magnum swap is so popular, real power, better MPG and overdrive.