We are talking about an issue so old that it may not be verifiable the easy way. That would be to look in the parts film or CD. I just tried this yesterday for someone asking about the 107 subframes and whether they still had factory help for failures. It didn't work.
What I would expect is the note that one original part was replaced (as of some specific engine number in this case)with an updated version. In the case of the SL all traces have been removed of the original number (I was trying to find out if the 380SL had the original subframe or was it only 450SLs). Being at home I can't check for you.
The way to visually check is to look at the rocker arms. The final fix had a very hard surface welded to the rest of the rocker arm. The original arms were all one piece and had the cam load surface machined out of the original material and then surface hardened. This was not enough and they had to change the material for the Cam pad. If you look under the cam pad it is easy to tell whether the thing is one piece or "glued" together.
It really doesn't matter what you have if its wore out. You will be getting updated stuff if you replace with new parts. (unless you use the wrong aftermarket stuff). If your tech says its worn then I would take his advise.
Bosch Master, ASE Master, L1
33 years MB technician