I'm the second owner, so not sure about the tune-up.
The service book has been stamped by the big MB dealer in Dallas (********) so that's been taken care of -- other than that, no other receipts. Runs and drives strong, with no oil use, or anything awry.
When I bought it, it was checked over by 2 different shops, and I got a thumbs up. Of course that was years ago, so it's only a matter of time before a real "issue" crops up.
The 120k mile service is coming up soon (this spring at the earliest), so will probably have it checked out then. For now, I think we'll just live with it.
Thanks for all the info guys!