Cummins don't have glow plugs, so you can as many miles on it as you want and dont have to worry about that. I have 202,000 miles on my truck now with my third injection pump. I think I might have got a good one this time. I hope at $1,600 a pop.
Tranny's on my gen. truck suck stock but if your not modding it and new valve body and converter will help bunches. Injection pumps are junk. Never had any problems with front end issues.