Follow-Up:

After a few days, the "slight vibration" that remained in the drivetrain is gone. I guess something that was slightly askew must have settled back into proper position down there. Looks like this one's a wrap...

__________________
Eric

1991 560SEL-Euro (214,000 miles)
1989 420SEL (Retired from daily use at 325,000 miles; Use as donor vehicle)