that size is real tough. most of today's cars (since they are near copies in transmission specs/layout) are between 169-172t front, and 59-63t rear. they are all 3mm pitch (almost everything 1/10th scale is).
you may have to go outside of the r/c industry for it. try doing a search for 's3m564', and 'timing belts'.
try also:
www.fennerprecision.com
www.beltcorp.com
that should get you started. pity they don't keep 'consumables' around longer for those models.