What's the best diesel engine to put in a 1977 ford 3/4 t pk to replace a 400 ci

What's the best diesel engine to put in a 1977 ford 3/4 t pk to replace a 400 ci

A small caterpillar would be best.

Scooter may not know that Cat doesn't make "small" engines. The smallest thing I've seen by them was their 7liter RV engine which they quit producing several years ago. All they make today are industrial equipment engines. Considering that you'll have to find a transmission that will work with whatever you get I'd say Cummins as that's the most common one. They're used in Ram's and in many RV's so transmissions are readily available also. Hope you have sme one who's skilled at rigging and fitting as it's going to take quite a bit to fabricate the mounting, for what ever you decide on, in that truck.

So I guess you're going to replace the entire exhaust system, fuel system, cooling system, add the wiring harness, turbo and intercooler, etc, etc.