Renegade Hybrids kit with offset rear tranny mounts. The large bolt from the Renegade spacer to the poly mount keeps coming loose. I've been using my impact to tighten it back down. Seems like the left one is the trouble. I may need a jam nut to keep it tight. Anyone have this problem?

no, but try some self locking nuts maybe? locktight? or pin the nut with a cotter pin (castel nut)

Is the poly mount deforming? I went back to 911 sport mounts to solve the problem.

It is a little. I bet that's it. Torque from the engine rocking the bolt on the poly mount. At least I can feel it come loose on the shifter (bouncing) before it comes completely disconnected.

I even built an aluminum cage to contain the plastic after being told told that I was the only one on the planet that had this problem. Kinda doubt it...

And no, I didn't over-torque them. The cage solved the problem but when one broke recently (after many years) from aluminum fatigue I decided to replace with the sport mounts. They're stiffer than the normal 911 mounts, cheaper than they used to be, and certainly quieter than the hard ones. Pelican parts has 'em. If you go that route make sure you still have the original mounting hardware or BIG washers.

If my shifting is vague I'll make some from scratch that will work.

Good luck

Had it happen to me after we first buttoned up the car, I've only checked it a couple times since then, Right now they are tight.. But I have 911 mounts.

When you tighten it down, does the spacer touch the polyurithane or the metal on the mount first? I remember back when I had poly rear suspension bushings, The bushings were not installed correctly and thus touched the suspension ear before the metal insert did, Therefore whenever I torqued them and put any movement on the suspension it would loosen the bolt.

Could be the same kind of issue...