Back in the 80s we bought about 8 syncrons and a dozen AKG451s from a local studio. The Syncrons had been modded to run on 48V but still had that annoying connector. A run to the tap and die shop with the mic bases and some Switchcraft XLR bodies and we were in business.
The 2 that I still have are currently kaput, one day working, a month later, nada. Nothing obviously broken and, as the amp is set in some epoxy/ silicon, a pita to get into, so there they sit, superceded by nicer mics.
If I remember right ( from the old r.a.p. usegroup),Dan Kennedy has some info on these.
Karl Hoffmann