Patent Pending kettles should be from '69-'70. Possibly late 1968 for the 1969 model year.... Patent numbered kettles should be from 1971-on. Harris I forget, how did you determine 1973 as the year of the redhead? It matches the 1971-1975 specs and cosmetic appearances, but was forgetting how you pinpointed the year? BTW, that is an awesome collection of cookers you got there. I'm diggin' that 'cado 22.