Nothing- - - - -repeat, NOTHING beats actually looking at the main bearing bores in the block to see which type of bearings you need. This is not idle chatter- - - -I've "been there- - -done that- - - -got the T shirt!" When we rebuilt John's 261 that the seller had described as a "1954 with a high water pump" I sourced main bearings based on the block casting number- - - -the hard to find ones with the dowels in the upper bearing shells. While doing the block cleanup prior to reassembly, we discovered that the block was a "replacement" item cast in 1959, and it had been machined for the later model bearings. So- - - -since the proper bearings were not available locally, I did the logical thing and drilled the main bearing webs to accept the older style bearings. Now the next guy who gets into the engine can use either style as replacements if it ever becomes necessary. It probably won't be me- - - -unless I set some kind of old age record!
Jerry
