Virtually all the 4-bolt main bearing engines have a letter code suffix to the stamped number at the front of the block beginning with a "T". I scavenge wrecking yards all the time for core blocks with 4-bolt mains to build my roundtrack race engines, and I've found that virtually every one I find with a "T" in the suffix code is a 4-bolt.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!