steering arms are definitely g40 specific, they have metal bushes in the middle joints but these have rubber boots over them so I guess you could be mistaking them for rubber bushes. Or it's perfectly possible that someone has replaced them with non-g40 ones in the past.
I've never seen a mk3 polo with adjustable arms on both sides, no idea where someone would have got a drivers side adjustable arm from! Are you sure about that, did it definitely have the nuts on the arm to adjust it?