Could be an uncommon variation of #15, but the color is similar to the #52 Five Gaiter, with grey hooves and bald face. That color of the Five Gaiter was around from 1963-1986. Unknown if any of these models have the USA Stamp; however it does not appear the mare had the USA Stamp. The FAF only wore the USA Stamp for a limited time during 1970-1971. Also unknown if the Foal ever had eye whites.
Overlap production years between #15 FAF and #52 Five Gaiter is 1963-1973. Estimated these were made sometime from 1963-1969 (based on the Mare not having the USA Stamp).