in cab gas tank question

[70chevlow]

I have a 1970 chevy c20. When i purchased it it came with a tank mounted in the rear but id like to go back the original in cab setup. My question is the tank i purchased was from a 68 and has 8 or 9 holes for bolts and when i look in my truck there are only two holes for bolts and it has brackets that are for straps so what is going on did the c20 come with a different tank.

[leftybass209]

There should be a row of bolt holes along the bottom of your cab. The bolts go in those and tighten down on thick metal tabs that hold the bottom of the tank in place.

[67CC]

I believe there are nine holes which should be on bottom, top and sides. I replaced the one in my C20 and it was just like that. Bought a new one and that style was the only option.
Are you sure those things are for straps? May have been something someone added later and they are hiding some bolt holes. If it's part of the cab structure and is on the bottom, those are for rubber mounts the tank rests on.