I have decided not to fight the alloy fight anymore, so I am replacing all my "Bad" alloy tanks with nice safe steel 72's from the 60's and 70's.
As for the Catalina tanks, any shop that refuses to fill them because they were made before 1989/90, even though they are 6061 alloy, deserves to go out of business as they cannot read, understand, and or train their tank inspectors correctly.
And the shops that will not fill any tank before 1989/90 steel or aluminum should have gone out of business a long time ago. They can't read or tell aluminum from steel.