The old pioneer connections are dirt cheap. My old machines had them on them. After I got the S 510 I changed to the flat face connectors on all my attachments and the 542B so I could use everything on both machines without changing couplers back and forth.
That was about $600.00. Those are about 8 times the price of the pioneers.
I have a drawer full of the pioneers now. LOL, probably never use them.