I've read in another thread on this site that some members have the know how / data to relate frame numbers to date's of manufacture? I've been intending to find out the dates for two projects (cb500f's) I got off ebay, I'm fairly sure the rustyest example is a '72 example, got a few interesting features too, like a cruise controll function on the throttle? looks too well done to be a diy job really, and a pretty cool exhaust, Dunstall I think. The reg no. on the other leads me to suspect it's a '73 example but it could be a '72 if I was really lucky. Are there cirtain prefixes that could tell me year of manufacture? I'd love to dodge paying road tax and if I've 2 tax exempt examples there'll be one more on the market for another skinflint...........