I tend not to think its either the flex disc or the differential mounts, but I could be wrong. The reason I think this is that when I shift into gear nothing seems to happen in the transmission itself for a second or so, then it bangs into gear. Also, there is no driveshaft vibration, and the car seems to track perfectly straight. I'm afraid it might be the transmission (already had the transmission filter and fluid replaced), but don't know for sure. Maybe low pressure to the clutches? Any ideas?
1986 560SEC: 150,000 miles, runs great, but I've got to sell it (too many cars for one man)
1987 560SL: 122,000 miles, used to run poorly, now (thanks to forum), runs great!
1997 GMC Jimmy: Turned out to be a turkey.
1989 T-Bird Super Coupe: 150,000 miles, still runs great. Ford got it right.