There are some 1920s Buick engines that were OHV 6 cylinder, with a cylinder that bolted to crankcase like that. Hard to say without a closer pic if that’s what you have.
I don’t know what engines were used in super early, heavy duty, GMC. They did use some engines from other lines in their first couple versions of half ton trucks….flatheads from Olds and Pontiac.
Last edited by JW51; 03/17/2024 8:19 PM.
