Ed
Did you work for Fram in Providence, Rhode Island.
I was under the impression that the filters were manufactured there for some time and at the sister company in Stratford, Ontario, Canada.
I know for a fact the Stratford facility manufactured the oval filters in the 60's.
Therefore there must have been two sets of tooling, one in Canada, one in the US.
Would that offer any accounting for the flared and non flared or did they wear at the same rate depending on production.