Well, I guess I will go open kimono.... I actually had a spare starter from when I transplanted a 250SE engine into my 230SL. It had the same configuration as the 'new' 280 starter - larger than the 230 starter with the through hole on the bottom. I can't remember the specific pn, but given my web research it seemed that Mercedes had a fairly common starter across the fleet, and that the part number rolled often. I was working off the Bosch pn on the starter, since I could not find a Mercedes pn - maybe that was on the paper labels on the starter that were no longer even close to readable. That starter had been sitting up in the loft for the last 12 years or so, and I am finally going to get some use out of it!!
I did do research into a new (actually Bosch rebuilt) starter, and was going to go with Autohaus AZ. They have a good price, and I have successfully dealt with them for several years on parts for the 3 cars in the family. If this 'free' replacement starter has no longevity, I will go with the Autohaus alternative. Since I am working now on my missfire problem, I have not really had an opportunity to get it out for a drive. Waiting for a new dist cap and rotor, and then if no joy a new Pertronix......
Thanks -- Roger