Try this site for Australian part numbers.
http://www.motorcycleland.com.au/yamaha_search.phpAs already stated in above post
This Yamaha 363-11633-00 PIN,PISTON part is also used on these models and components:
1973 SC500 CRANK - PISTON
1974 SC500A CRANK - PISTON
1974 TX650A CRANK - PISTON TX650A - XS650B - C
1975 XS650B CRANK - PISTON TX650A - XS650B - C
This Yamaha 93310-22062 BEARING,CYL.#10 part is also used on these models and components:
1973 SC500 CRANK - PISTON
1974 SC500A CRANK - PISTON
GASKET, CYLINDER HEAD (363-11181-00) part is also used on these models and components:
1973 SC500 CYLINDER - REED VALVE
1974 SC500A CYLINDER - REED VALVE