You can swap a 2.4L OM616 Benz in without too much issue, just a 3/8" adapter plate, a custom pilot bushing and some light machining of the benz flywheel(chamfer the outer edge a bit more) to clear the tranny housing.

Not as straight forward as a direct Mitsu diesel swap, but it is an option.

1989 Dodge Power Ram 50 w/ no engine <- rotten frame <img src="/forums/images/graemlins/frown.gif" alt="" />
1988 Power Ram 50 2.6 Long Bed
1990 Mitsubishi MightyMax V6, swapping to the Daimler-Benz OM617 3.0L I5 diesel