This has probably been discussed before, I want to see what you guys think. What is the best diesel engine reliable wise out of these 3. My fav is the 617. However I have two diesel a 1992 300sd and a 1986 300sdl. Both are #17 heads. Both leak oil at the headgasket which I hate. My 1992 leaks pretty bad. I am planning on doing the headgasket replace myself.

1. 617

2. 603

3. 606