They will work fine. Most of the later SY/TG synths and the RM50 and RY30 rhythm units used Yamaha's SY/TG77 waveform cards. Yamaha didn't change the card type over that series.
If it has a waveform card slot it will accept a SY/TG waveform card.
[This message has been edited by Nigel (edited 05-01-2003).]