403 Oldsmobile

[SSDiv6]

Originally Posted by Bob Shaw

According to the late Joe Mondello there were about 2500 solid main web 403 engines built. Most of them were in 1977 Buick station wagons. Block casting number is 557265-4A or 554990-4A. My son has one in his Cutlass.

Bob,
I have built engines with both casting numbers and the mains are hollow. Has your son torn apart his engine and looked at the block?