Ok so I putting a 16 gal mustang tank in my 69.5.... it has the ca smog filler. I remember how much of a pain it is with fuel pumps and was curious if any one has found a better neck to use....
I swapped from a 73 to a 77 filler tube with the flap door and I had a lot of improvement. Some people have had similar experiences others have said it doesn’t make a difference.