Ordering parts online and sites listed the incorrect belt size. I don't have the cardboard sleeve anymore, therefore returning is not an option. This will fit the 123 and w126 primarily. It was on the vehicle but never ran as I could never tension it. Might be a little dirty, but still smells like new rubber. Never used.
Technical Data Manual states:
Standard Engine m110 w123/w126 (starting 1980)
AUS/J/SA/USA Engine m110 Starting 1981
That is what I am able to confirm.
Shipping only includes 48 States additional area will incur small added shipping cost. First class mail.