[rotorwrench]

As far as I know (which I will admit is limited), the Canadian trucks came from the same plant whether they were Ford or Mercury at Walkerville at least till the Oakville plant was built later.

I think what Tubman was trying to get across is that Mercury engines generally used the 4-stud Holley 885 type carb so they had a different manifold and air filter. Ford US didn't put a 3-stud model 94 on a Mercury engine for the 8BA era. They generally always used the Holley 885 to the best of my knowledge. I can't say about Canada for any certainty but it does make a person think about what they were doing there.

Mercury heads would have been comparable to truck heads for compression but they aren't the same. They are close but not the same. Trucks pulling heavy loads had to have lower compression and gearing for the engine to survive. Mercury heads were not as low a compression as truck heads but not far from it. They lowered the compression due to the increase in cubic inch displacement to keep the overall compression about the same as the 239 CID engines. This would lower the possibility of detonation under extreme loads. This is why I question the use of 1CM heads or any Mercury heads on a truck for that matter.