[THEFERMANATOR]

First I would reccomend crunching the numbers for your fuel savings VS the cost of the repower. A V-20 is gonna need a LIGHT diesel which limits your options down to a few of the modern diesels with alot of aluminum in them. The only one that is priced even remotely reasoneable that would push a V-20 is the CUMMINS 120HP with the ALPHA 1 outdrive, and it's track record has not been the best from what I have read on it. Maybe one of the VW engines they have out now would work as well as the D3 VOLVOS, but the cost on those is UP there. Unfortunately the weight of CUMMINS 3.9L or the GM 6.5L would both be too much for a V-20 to take when at rest and would result in VERY poor balance. Also remember that diesels make ALOT more torque than there gas counterparts so the ALPHA(or your current outdrive) will not be up to the task, so you'll also have to figure in the cost of that. For the money I would keep the 165 6 as it isn't that bad on fuel for a gasser, or repower with one of the new 3.0L at 135HP as they are said to be about 20% better on fuel than the 6.

For a V-20 the best option if you want cheap diesel power would be to go with a jack shafted 6.5L or a small PERKINS or something IMHO. You would also have to go with BRAVO 1 or a VOLVO outdrive to handle the torque, but the jackshaft option would even out your balance in the boat.