Hi Brian, Welcome!!
Since your car is a St. Louis built 1981, you won't be able to request a build sheet, only the Bowling Green Built 1981 are able to do that ...
Have you looked for your original Build Sheet? The factory placed one on top of your fuel tank. You may be able to see it from the gas tank lid, by removing or moving the rubber catch basin and using a small flashlight look down onto the top of the tank. If not, you can sometimes reach up around the tank and feel if it is there.
The spare tire storage compartment isn't real hard to remove

but if you are thinking about loosening or dropping the gas tank be sure it is EMPTY or as EMPTY as possible, gas has more weight to it than we all expect

If you do see the build sheet
Be very Careful touching it, REMEMBER the sticker is paper and been there for more than 23 years!!! it will crumble just by blowing on it... (That is if it is still there!!)
Tracing the previous owners can be extremely challenging... I think in the Tech Center or maybe the Portal at the top of the page is a brief outline on helping search for previous owners. I think some, but NOT all states allow access to their DMV records.
I was very fortunate I am the 3rd owner and both previous 2 owners documented every tank of gas, oil fill and even saved old parts.. so I have window sticker and all original owners pamphlets and all, even have the original 255/60/15 Goodyear tires...
Good luck and happy searching..
Bud