Well, I purchased an A12 new in the spring of 1969 and in upgrading to a electric fuel pump from the back frame rail,
I can unequivocally tell you that I replaced the 5/16" line going to the mechanical pump.

I'm 81 years old and have pictures of my car on the carrier next to my buddies (a salesman at the dealership) M code Barracuda.
Those were the days!!!

Joe