Popping out of reverse?

My 89 had a 5 speed put in it by the previous owner. It shifts well, everything works good. But I have to hold the shifter back while in reverse or it pops out.

I've heard there is an adjustment or some such to fix this. Anyone else heard of this before?

a 5 speed was put in? does this mean that it was originally an auto. perhaps the shift lever is hitting the body in some location. maybe only while in gear due to a worn engine or transmission mount.

you mean the thranny is moving when I start reversing? I hadn't thought of that. hrm...

My girl's TJ did the same thing after installing a new lift it was from body interference. The trans shifter was not properly lined up in the hole anymore. It had shifted forward just enough to made contact and strangely only in reverse.