Thats very true.
I tried to order 3 different tanks for my 71 Ranchero and all of them were wrong. One was for a semi I think.
I wound up finding the specs for the 71 tank and found the tank from a 73 F-350 [rear mounted] was all most the exact fit for my Ranchero.
Mounted the in tank pump and added two small pieces of rubber and bolted it up.
Greg