I busted my rear drive shaft out of my 90 Cherokee. One of my buddys had an extra one laying around that was about 3/4" longer. Well I put it in anyway just so I could drive it but now the slip yoke is almost completely in, is this a bad thing or do I need a shorter one? I've hit bumps and jumped up and down on my back bumper without it seeming like its under any strain.

 

well the worst that can happen is that you crack the case or ruin the bearings. if you are lifted I would not worry to much, if you are stock I would get the proper one.

the axle and tranny combo have alot to do with length

 

I'm running a 3.5 inch lift but its still got about 1/4" between the Tranny and the shoulder on the slip yoke. Still think I'll be good as long as I don't jump it?

 

I wouldn't count on that. JY driveshaft now could save you buying a t/case later. You roll the dice on that one......

 

What you did wasn't a good idea. The slip in the yoke is there for a good reason, to allow travel of the shaft when there is movement between the rear suspension and the transmission which ultimately occurs when the rear axle moves up and down. You eliminated that. With hard driving, or maybe not so hard, you'll create a reason for replacing driveline components and maybe even a tow possibly from the worst possible place. Put an original length one back.