46Dodge, my W124 is a 'run of the mill' 1994 E320 and I'm looking for rear glass too. For my car MB has none in stock in the US. Safelite has 8 or so, all in California, and they don't transfer or ship ( I live in Albany, NY ). I'm waiting to hear back from a local indy glass shop. They do most of the glass work for our local dealer. Mygrant is the US distributor of glass to all MB dealers. Hopefully they'll have an aftermarket piece in a nearby warehouse that the glass shop can get their hands on.
In terms of installation, ask your local MB dealer who they use. You can also call around to local indy glass shops and see if they have experience with older Mercedes. In my area there really is only one top notch shop which as noted does 95% of the work at our local MB/BMW/Alfa/Mini/Honda dealer. YMMV.
Regards,
Peter Weissman
