Yeah I’m not sure why. Actually Scott Smith from harms carburetors and I talk to Jim ( I believe) at 521 restoration to get him to make the correct bottoms of the fuel tanks. I tried to get him to make the 70 tank but he did not want to make the one your only tank. I tried talking to spectrum years ago and they say in the parts book it’s correct so they weren’t gonna change it, also talk to vans who makes gas tanks they said the same thing but they are all wrong