333882, 1.94"/1.50", 76 cc, 137.5 cc intake, 95.4 cc exhaust, production 1974-1980

3970126, 1.72"/1.50", 75 cc, 148.3 cc intake, 87.6 cc exhaust, production 1967-1971

I'd use the 882 heads for the induction hardened seats over the 126 heads if I had both sets and was desparate/broke/doing a stock rebuild.