Tracy,
The M-100s are the three Mercedes models powered by the M-100 engines. They consist of: 600SWB, Pullman and Landaulet, the 300SEL 6.3 and the 450SEL 6.9.
I own a '79 6.9 and it's one of those "banker's hotrods". Kind of like the 500E of the '70s. You can find all the info you are curious about at
http://www.m-100.org
Last year, the M-100 Group show was in Portland, Oregon but I missed it due to transmission failure the week before we were to leave Ohio! I could've hopped a ride with some guys from New York in their 6.3, but I decided it was best to save the trip money to use on the transmission rebuild.
My fiance' has been trying ever so hard to convince me to pick up and move shop to Seattle. Although she's actually from Olympia, she loves Seattle and keeps her eyes open when she's out there for old Mercedes so she can build her case against my hesitation to move!
I will admit, the view from her parents' house onto the Puget Sound is better than our view of Lake Erie, lol!