In 1993 the production of NEW R-12 ceased but a few vehicles used it into 1994 but not many. It could be either and now old enough it could be converted and should be marked.
At any rate you should be able to tell by the fittings. R-12 use threaded fittings and the 134-a always used the quick connect Acme fitting and you should be able to see if they are adaptors or original. Sticker if still there would say what it was originally.
Where I am it's hard to know if a system is working as it's mid Winter where I am. You can usually get a clue by running heater full blast till it's way too hot inside car/vehicle. Shut down so engine heat fills engine area for a couple minutes and start up watching, touching - anything you can to see compressor engage quietly, and carefully feel for warm outlet line with now A/C on full blast. It can't really tell that it's perfect but a good clue that it's operational.
It would cycle off quickly if cold ambients prevailed as it would normally in cold weather. If above 60-70F you have a chance of more knowledge of if it can work well.
Suggest that if the vehicle you are considering has R-12 and is in nice shape that you don't pass it up over this. Within the same model year they could have used either and switched mid year,