I have a 91 jeep cherokee and i just bought a new upper trans cooler line. the line coming out of the radiator will not fit into the new line end. why is this was it just a bad part or is it something else. all input helps.

 

Is the leak in the rubber line? If so remove the squeeze clamp holding it right above the fittings and pull the rubber line off.

 

I see that this is an old tread, but I recently had the same problem. The metal line (that attaches to the radiator with the flare fitting), the other end is too long for the new replacement hose fitting. I had a factory metal line and new hose fitting. The metal line would bottom out in the fitting and it would not grab the crimp bead on the metal hose. So I ground down the very end of the metal line (below the line crimp/bead). After cleaning the metal and smoothing the end I re-inserted and it fit nicely. The seal here is an o-ring seal, so as long as it goes in and locks it is fine.