Hello. I am buying main bearings for my 64 Olds 394. Many sites list main bearings from 1959-1960 for the 394. My question is do the main bearings change in the 394 anytime between its production from 59 to 64? Same with connecting rod bearings?

 

Yes , they did change the mains in the 394's production run .
The front main was changed in 1961 , so it's 59 - 60 and 61 -64 .
The second , third and fourth main changed in 1962 . So it's 59 - 61 and 62 - 64 .
The rear main was all the same 59 thru 64 .
The rod bearings also were the same 59 thru 64 .