From a March 31, 1967 Technical Service Bulletin article letting the dealers and service managers know that there was an issue and how the factories dealt with it
One thing I found interesting as a side remark is that in this bulletin Ford suggests the stamping found on the drivers side block extension as a date and initial of the inspection rather than the assembly as they had in other documents. Maybe just a mistake in this one. Oh well not the major focus of the bulletin but thought it was interesting. Will need to see if we can find another document that supports that statement and start another discussion