Repair-It

So after replacing rear differential mounts that were visibly torn and motor mounts that had permitted inches of engine displacement under torque, I still have a low-speed, torque-related vibration. Further inspection it looks like the driveshaft has no visible issues and I don't feel anything odd, wrong, or any play in the cv joints or "rag" joint at the rear. I do however, find that the carrier bearing support in the middle of the two-piece rear driveshaft appears to be excessively "soft", which makes me think that the rubber isolator around the bearing is tired. The OEM strategy is to replace the entire driveshaft assembly as a unit, but that's $787 from RockAuto for Mopar, or $581 for Dorman.

I'm considering doing one of these, but I was hoping to find a similar product for a lot less $:
https://www.jxbperformance.com/products ... er-upgrade

Those center isolators are normally pretty soft. Like you would be able to displace it almost an inch including the +/- direction on a properly functioning one. I have not found them to be super stiff. As I have said before, all I've ever heard (since my CTS-V days) is the center bearings can go. I've never really heard (or don't remember) an issue where that isolation fails before the bearing and causes your symptoms. Doesn't mean it isn't but it seems uncommon at least in my travels.

Check those giubos for fine cracks. They can cause issues long before there is an obvious chunk missing. But, everything would point to higher speed issues.

I've seen others that have built temporary molds/dams and injected RTV-type rubber in the space for things like differential mounts, like window installation urethane or similar. I think I have a tube from JCB window resealing kicking around. Might be worth experimenting with.

There are other options...
https://makodriveshafts.com/products/re ... -2010-2018

I guess this would be a candidate to try to attach a "sports" camera (GoPro?) to the undercarriage and watch it during a loaded take-off to see what's actually going on.

Subaru WRX guys and Mitsubishi 3000GT/Dodge Stealth guys seem to recommend RTV in lieu of something stiffer/harder. I do have some gray RTV in a caulk tube kicking around.