<<Thanks John!! Keep stubbing me toe on a pipe that emits from the 1955 3703524 block. Any idea what code V12371 or I stands for?? >>
The first-year-only '55 524 block had a road draft tube installed inside the back of the block, between the rear face and the flywheel; you can see the cast-in opening for it near the top left of the photo below. That hole was removed for '56, and the road draft tube became external.
Is that code stamped on the front pad on the '55 block? If so, it's not factory - the "V" prefix wasn't used until 1967 (the "1237" part doesn't make sense either). Got a photo?