Seeking edgucation about factory installation of carpet

[mr.mud1]

my 72 Cheyenne Super C-20,YE9 and Z84 custom sport truck, built in Fremont,Ca,has carpet and pedal trim,but not called out with all the other RPO options on the bottom part of the build sheet.it does say on the top part,in box 92 "mat carpet front" AF- and the next block 93 says "mat carpet rear" and says open,the next block isn't numbered but also says open.i'm guessing suburban?i could be wrong and probably am but i thought the trucks that had gas tank covers,were bucket seat trucks?i have never had a bucket seat truck but don't remember a gas tank cover in and of my bench seat trucks?there isn't one in this truck.