Yesterday while going thriough a salvage yard with a friend who is building a y block we pulled a few sets of rocker arms... one set had part # ECG 6564 A2 on all 8, another had part # ECG 6564 B2 on all 8, and the third had part # ECG 6564 B2 on 7 and 5751066 on 1... I thought the ECG 6564 a were the 1.54 ratio rockers while the 5751066 were the 1.43... if I am wrong please let me know... and why would some one put 1 1.43 on with the 1.54... also are the valve adjusting screws interchangeable?

John