Interesting observation
 

I just replace the rubber fuel line from my fuel tank to suck side of my Holly Fuel pump. I stopped at the marina to get new line and all they had was stamped 0350-0380 SAE J1527 USCG TYPE A1. OK fine but it was 6 bucks a foot. I had a small piece left over and it appeared to have a larger ID than the hose I had been using. Previous hose is stamped SAE J1527 USCG TYPE B1 315-0380.

Checked diameter by inserting various sized pencils. The replacement hose is just a tad bigger, both are 3/8 line. Clamped down on the fittings just fine. This is good thing as it will allow a slightly higher flow rate.