Acquired a 312 ECZ C block and crank this past weekend from a new Forum member (thanks gambo)
While I was picking thru the stuff it became apparent that this was a 56 block (casting date of 65) with "C" heads and the 56 camshaft arrangement.
It appeared to be all original with this being the first time being taken apart.
It had truck mounting timing case cover,front mount,bell housing,truck tranny and was painted gold/yellow as a Mercury would have been in 1956.
Do you guys think that Mercury"s 1957 pickup being sold in Canada used the 312 engine.Or perhaps this may have been a 56 Mercury pickup truck.This also looks to me to be one of the earliest casting date code of a "C" configuration block that I have encountered.
It sure puzzles me. 
Whadu guys think ????