Should I perform a differential change if the case is rusted? I'm nervous it will do more harm than good. The truck has been in Ohio all its life so it has a rusty undercarriage. The last thing I want to do is strip/break a bolt. The truck is a 2000 Ford Ranger 2.5L 5sp 2WD. It has 101K on the clock and probably has never had a transmission/differential change. Should I go for it?