I had purchased a replacement block for a 1948 Cub that had a block beyond repair. The serial number is FCUBM274374. Having trouble trying to figure out the year it was made or put in service. Looking through several lists available none of them seem to go to this high of a serial number. When I received it the starter and hydraulic pump holes had plates over them. Also, there were "L" brackets mounted to the bottom of the block. It looks like it may have been used as a stationary engine. The casting number is 251341R8 with L3. There is also a circular date code with 12 over 3 and an 8 3 horizontal. There are two photos attached that are not the sharpest but show the numbers cast in the block. Any help to know the year it is would be appreciated. Thank You