Maybe it is a truck flywheel
All the early, pre 1962, 8 bolt crankshaft don't have a centering register for the crankshaft or flex plate to ride on, they center on a machined surface on the outer edge of the crankshaft and they normally have studs, bolts in them with no threads in the crankshaft flange for the bolts to screw into
I have seen that type of flywheel used in Mopar SB with small C.I., less than 400 C.I., in some of the old modified eliminator cars