i know my 4runner had a locking gas door, but did the pickups ever have an option for them? Wether it had a release from inside the cab or a key on the door?

 

Some of the pickups did. From what I have seen, only 2WD trucks that had the Japanese style bed had locking fuel doors. They are just a simple lock cylinder with a tab that catches on a metal bracket.

I think only 4Runners had a release style fuel door that had a release inside the cab.

I am not sure if the fuel doors are interchangeable because they are part of the fender/wheel well arch. Someone here may have tried but I do not know...

EDIT: It appears that the fuel doors are a little different between the flared wheel arch and the Japanese style wheel arch, particularly the angle at the bottom left corner.

I have seen locking gas caps but I am not sure if they were original or added on later.

Here is my 1987 2WD truck. It has the Japanese style bed with the locking fuel door.