I find 4 leg 18" toms as early as a 1967 catalog thru 1975 catalogs. And 3 legs seem to start in the '76/77 and later catalogs. Maybe one of the first 3 leg models?

I special ordered my 18" and 20" floor toms in 1975 as part of a 10-pc double bass kit, and both FT's came with only three legs. 1975 was the last year of the Swivo era Fullertons before the transition to the Big R Memriloc hardware in 1976, and Rogers was already starting to implement some cost-saving practices not depicted in the catalogs. Besides the switch to three legs on the 18" and 20" FT's, 1975 Fullertons incorporated a few other transitional features. My 1975 script-badged 6[SIZE="1"]1/2[/SIZE]" COB Dynasonic has the newer Big R style snare gates, and my twin bass drums (in black ebony) have black hoop inlays rather than the silver glass inlays traditionally used on black basses up to 1974.

So if you see any 18" or 20" 9/72 series FT's with only three legs, they are probably late 1974 or 1975.