I agree with your friend. With internal threads and ridges for a clip-on hose it sounds like 134a. Also, 134a fittings are a lot bigger in diameter than r12. The suggestion above that someone might have stuck on whatever they had at hand is a worthwhile caution, but it's easy to test.

Conversion kits have a 134a style fitting that screws onto the external threads on the r12 fitting. If you can start screwing this off, it's a pretty safe bet that it has been converted and it's 134a. If it's integrated with the hose the whole system has probably been replaced, and this is unlikely in the extreme, but makes it virtually certain that 134a is right. Either way, if it's got a 134a fitting, it's not a bad bet that the system has been converted.