Hi Scott,
You're pretty much out of luck there; Victa's dealer parts lists never gave full fastener dimensional specs [unlike say Honda's parts lists], in either of the 'Green Books' [a two volume set, that came in green ring binders] that were the master parts lists back in the 1970s. Only part numbers.
In the 1970s and 1980s, Victa could still supply most parts for their 1950s models - except for superseded items like the 9B blade disc.
My family's OPE business still had NOS blades, bolts and bushings for the 9B, but we would just fit a complete 9C assembly to any older mower that came in for service, needing replacement blades. Victa supplied the 9C discs with cutting blades already fitted, for a good price.
