John's 261 engine we rebuilt a while back was a high water pump type normally associated with 1954-55 production. However, it has a 1959 casting date and a blank number pad by the distributor, and the main bearing bores are machined for post-1955 mains. It has to be a factory-replacement block cast using the early mold, but machined to post-55 specifications. That made fitting the main bearings an adventure- - - -requiring a little block modification to accomodate the early style mains we had on hand!
Jerry
