1968 ( 318 ) main bearings - Input requested

SGBARRACUDA said

Chris the difference in SB and BB in 74 was the Width of the thrust bearings.
Main bearings for 318's changed in 1974 to a different thrust width, pre 74 used (for example) Clevite MS-540p with a max thrust diameter of 3.374 inch, then 74 on used Clevite MS-1344p with a max thrust diameter of 3.530 inch.

Click to expand...

The change to the main bearing flange was also cut in the blocks before the 'official' change... I have seen a few blocks earlier than 74 with the wider thrust flange machining...

Check your block before ordering...

However, the early style bearings will still work with the wider cut flange...