mine is from '72. earliest CD50 I've heard about was one from '69. they were produced till the early '70s, without any big changes. you also had a CD65 and CD70. same rolling frame, larger engine.
then you had a K1 model. and later some honda japan models. they stopped making them only a couple of years ago I think.
only the first model had the gas tank with chrome side panels.
the first fenders were plastic, these are no longer available.
the later CD50's had the same style fender but in metal (difference: more rivets, and they're painted over). I don't know if you can still get these from Honda, but there are a couple on Ebay and webshops like CMS and Davidsilverspares have them (pretty cheap too)
honda part number for the metal fender: 61100-065-010
CMS:
http://www.cmsnl.com/searchparts.ph...oduct3=010&partslistPageSize=25&totalresults=
Ebay:
http://cgi.ebay.com/ebaymotors/Hond...8856002QQptZMotorcyclesQ5fPartsQ5fAccessories