Apparently, these were some of the first few Blocks made to use in the Can-Am series factory supported racing. I am still trying to depict if there are any previous casting numbers prior to these...Note the bottom Block has this same # as well. The top Block to me is the aluminum walled NON-Iron Sleeved Block, having the same oil galley head supports casted in place(bore size observed will help seperate the 4.250 Bore from the 4.440 Bore). Also notice the clearancing manufactured into the Valve covers; staggered or long arm rockers?? I am unsure as to how further document thse Blocks as there are SO few left in existence!
