Had the same “55” on my 71 so just told people who asked that it was my “I can’t drive 55!” Statement.
Those were impossible to get off in the junkyardin emblem collecting days unless a damaged fender had been pulled out of the way. That “4” always snapped off. I believe I have an NOS one of them in the box but wouldn’t sell but possibly trade for something equally cool for my 70 GSX clonester PM me if ya got anything.