[Baffler]

Not sure on the coupe but I'm led to believe all C70's have solid aluminum subframe bushings so you can probably rule these out.

Check the steering rack, on the LH side, where it sits on its mounting bracket. I've seen a few of these separate. Not sure how they're bonded at time of manufacture, no evidence of a weld, so may be a friction fit with a metal adhesive. The bracket is mild steel whereas the rack is aluminium.

My C70 failed its test on this very problem so, to remedy this, I removed the two screws for said bracket, leaving the bracket in place, and fitted a U-Bolt over the rack and through the bracket (with some PVC pipe fed over the U section to minimise metal to metal contact). Getting it to sit correctly, without applying to much downward force on the casing of the rack, is a case of adjusting the 2 upper nuts (bracket side) then tighten 2 lock nuts from underneath the subframe. Sounds like a bodge repair but has worked for three consecutive tests and saved an otherwise perfectly good steering rack