There are loads of other Yamahas that used the exact same disc as rear brakes; I guess it depends on whether you want to take a risk buying a 2nd hand item. Is it 245mm diameter?
All Bike Engineering list fork & disc measurements & state which discs match using handy lists in .pdf or .doc format
http://www.allbikeengineering.co.uk/discs.php
According to their codes, potential matches appear to be:
XJR400
FZ600
FZR600 89-93
FZR600R 94-95
SRX600
XJ600 Diversion 92-98
YZF600 Thundercat
YZF750SP 93-97
TDM850 91-99
TRX850
TDM900
YZF1000 T'Ace
YZF-R1 98-02
All Bike Engineering list fork & disc measurements & state which discs match using handy lists in .pdf or .doc format
http://www.allbikeengineering.co.uk/discs.php
According to their codes, potential matches appear to be:
XJR400
FZ600
FZR600 89-93
FZR600R 94-95
SRX600
XJ600 Diversion 92-98
YZF600 Thundercat
YZF750SP 93-97
TDM850 91-99
TRX850
TDM900
YZF1000 T'Ace
YZF-R1 98-02