Are these T/A heads?
many casting lists are off. 3418915 was used on 1970-71 340 with 2.02" intakes , and also some had intake pushrod holes machined spread for offset intake rockers on the six barrel engines. and 1971 360 with 1.88" intakes. date codes = 02-16-0 = feb. 16, 1970 01-23-0 = jan. 23, 1970