Tim, As stated above, *my* 261 is out of the '54 mold (per the casting code) and has no capt bars. And oh by the way, the 261s were *not* built in Quantico, VA so they would *NOT* be Marine Corps Capt bars
I wonder if the Capt bars are related to whether or not the engine is for an Advance Design or Task Force application -- water pumps are in different locations, and somewhere in there the main bearings change in how they are retained in the journals. Why is this important?
Read This -- why knowing your casting and date codes are important Not all 261's are the same.
Does *any* of this apply to Canadian engines?
Ya got me

As asked above, maybe one of our Canadian engine guys can tell us.