The February 1972 proofed one is a 1st quality and utilizes the Merkel patented Weichlot method of joining the tubes. I assume it has ejectors?

The November 1991 proofed Geco stampted SxS with H&H style locks and pipe style side frame reforcement is a Model 60E and I assume that was under unification of Germay. Is the tubeset length 68cm or 71cm? I'm sure you can get a copy of the ledger from Merkel to supply you with info.

Kind Regards,

Raimey
rse