The application for the patent that first introduced these frame ends with the two bolt holes first appeared in 1975 (May) and I've got a Guerciotti (sadly not mine, happily way too big) that was built in 84' with this type end fitted - so in short with that time span I doubt the existance or not, would be of much use for dating purposes (+/- a decade)
Off Topic - This Guerciotti must go down at the least subtle "classic" in existance. There are more yellow G's, stars and pantographing than I care to count (35 instances, I think it was) I mean - stripes pantographed around the brake arms in the national colours ! - Oh and more national flags than a Masi :0 - If that didn't convince you of the bikes origins - it has two "stickers" (not decals or transfers) declaring "Made in Italy" !
Best Regards
Bob Reid
Stonehaven
Scotland