Yes the casting number is for a 54 to 56 block, sounds suspect to me. When the 261 came out in 54 ,it had the higher mounted water pump with the 4 inch pully same as the earlier 216's.in 55 the 6 cylinder blocks were cast differently with a lower water pump mounting.So a block is either a 54 or 55-56, not a 54-56.So the old photo of a high water pump 261 I looking at can be a 56 engine? Unlike the 235 did 261's keep the early style block until 56? Or are the casting numbers incorrect?
This could be earth shattering information.
