Type 1 1971-1974 %40 silver including proofs/type 2 clad 1971-1978 unless its for a different reason.Because i know there were different types related to something about the design,the moon?if I remember correctly which was only for 1972.
https://en.numista.com/catalogue/pieces1346.html And for the 1976, https://en.numista.com/catalogue/pieces3366.html
There were 3 of the 1972 Ike dollar types: https://www.pcgs.com/news/3-types-of-1972-eisenhower-dollars
