main bearing drama

[Lawrie]

I,m assembling a C69a engine,I ordered the main bearings for 1939-1948, the rear bearings won't fit into the block ,they are too narrow on the id of the rear main thrusts,(D dimension) the overall width is right(C dimension) where they fit into the crankshaft,also they only have a narrow locating tag,where as in the block it is a wide style.
looking at my stuff it looks like the bearings I got are for an 8Ba.
I think I need the 81a-6331 style.
Am I right
Lawrie