If that block was actually cast in December of 55, likely that is a 56 production year block. The factory shut down for about a month starting September 1,1955 to retool for the 56 model year's offerings. A December casting date would indicate a 56 block cast about 2 plus months or so into the 56 production. So you might want to shoot a photo of what the main bearing saddle of your block looks like just to see if we can sort out and maybe confirm the main bearing issue. The earlier 54-55 bearings might be the wrong bearings. Also, might take a look at the distributor pad and see if anything is stamped on the pad. Lastly, when you took the motor apart, was there a rope rear main seal or an orange neoprene seal? When you pulled the crank, were there any thin brass shims between any of the main bearing caps?
Last edited by Dragsix; 06/09/2023 2:47 PM.
