[Bob B.]

The factory diesel options for a '72 C-60 would have been the DH478 Toroflow or the Detroit 4-53. I would say neither of those is really an option here as they required particular bell housings and mounts, all of which would be near impossible to find these days unless you found a parts truck so equipped. Further, there are no engine parts available for Toroflows anymore. Big surprise here is the 6.5L GM diesel has the same bell housing bolt pattern as the 366 gas V-8 and if you truck has side engine mounts they will also be in the same place. Some 366/427's use a front engine mount under the crank pulley, that might have to be fabbed up for a 6.5L. With the right clutch/flywheel you might be able to replace the 366 with a 6.5L without too much trouble. But, 26,000#'s is a lot for a 6.5L. A turbo would probably have enough power, but you would need to be careful not to blow the engine up, they really are not designed for that kind of service. As for the 4L80E, it should have not trouble with that kind of weight provided it is in good shape. The problem is of course you will need a computer to run the thing (available with harness from the aftermarket) and you would probably need a 4L80E with a parking brake (not just a park position) on the back. Those are out there, look for Isuzu NPR's and some 3500HD cab and chassis models, they had them.

Another option would be to try to find an 80's era GM C-60 or 70 with a Detroit 8.2L and an Allison AT 545. Not the greatest diesel Detroit ever made but would work well in that size of truck, and the whole powertrain is just about bolt-in.

Now, for the big question: Why? I understand if it's some kind of project truck and you want to put a diesel in it, but if it's just a work truck, you will spend a lot more converting it to diesel than you will spend putting gas in the 366 for a long time.