Diesel --- front engine -vs- rear engine

If you are talking about a FRED class chassis, it is basically a glorified gas chassis, with a diesel stuck in it. Not much of an advantage. Typically will not have air ride, and the engine is up where you have to listen to it. You take a hit on power and less torque at the drive wheels. Its not an idea that makes a lot of sense, unless you plan to put a million miles on it and can't afford a good sized pusher.

Dare I say its a lot like comparing a Harley to a Goldwing.