The early #Contax IIa (black dial) models don’t have a PC socket; instead, a mechanical pin is pushed out into an adapter — a #Mechanical timing device that delays the triggering of the flash.
Two versions exist: the 1361 for flashbulbs, and the 1366 for “Elektronenblitz” (modern flash).
I made a #Mod from a 1366 (Braun) to TS. It didn’t work at first until I found the adjustment screw under a cap. Now I need to find a way to confirm proper sync.