When the car was at the shop to get the weld repairs and driveshaft loop, did they do anything to the driveshaft? (Drop it, dent it or do anything to change the pinion angle?)
It's definitely not driveshaft or rear driveline related. It does exactly the same thing sitting still, in or out of gear, clutch in or out. That's what's giving me heartburn.
My brain wants to blame the recent work, but I don't see how it could have thrown the engine out of balance. He rewelded the O2 bungs and installed the Stifflers driveshaft loop. He removed a spacer I had under the transmission mount, but the loop is about the same thickness, so the transmission height and driveline angle shouldn't have changed much. And again, that wouldn't explain the vibration at a dead stop anyway.
Next time I'm under it, I'm going to check carefully for anything touching the body, transmission, exhaust, safety loop, whatever, that could be transmitting vibration into the chassis.
I'm grasping a bit because of the timing, but mechanically I don't see how the rear-end work itself would cause what I'm feeling.
