The Normal Observable Practice is the 1970 year had three different tanks.
The 1970 straight vented (Commonly called the 68-69 tank) Quanta Part #46A:
The 1970 angled vented. Quanta Part #46D:
The 1970 EEC non vented Quanta Part #46E:
Then in there is the 1971-1972 w/o EEC. Quanta Part#46C:
Note the last three all look the same. Not having the drawings the only difference is in the gas cap fitting.
It pays to make sure you have the right part number tank.
The 1970 straight vented was in my January car so was used past then. Not sure how far. However my July car has angled vented. Hard to track with so many replaced of the years.
Greg