So here's the plan: 1. 27' Class C RV that's just too thirsty: 2. Remove 7.5 liter gas engine & 3 speed auto transmission and replace them with these: A 5.9 liter first generation Cummins turbo diesel & an Allison 542 (with the 545 extra capacity oil pan) 4 speed auto transmission. Lots of the diesel conversion forums say it can't be done but I've seen a few photos and videos of those who have! What could go wrong?