IS A ‘65 383 BLOCK DIFFERENT THAN ‘66-72?

Cam kits show as fitting 67 and up. The reason is that the lifters in pre 67 big blocks had a smaller cup and used a pushrod with a tapered end and a smaller ball on the lifter end and standard size ball on the rocker end. I ran into that on my 66 361. Luckily Kim had a brand new set of early style Johnson lifters. I could have used newer lifters if I had switched to newer style pushrods which had the standard ball size on each end.