It's a chain hoist that mounts to a (missing) cross bar and the tire sits below the fuel tank. Yours may have rusted away. Just purchase a custom rear bumper with spare tire swing out...you know you want to!
Yeah the chain should be hanging down, so it is definitely not there. A bunch of people remove it because it hangs low under an already long tail, and can cause problems off-road. If you don't get a rear bar mounted carrier (which you can make if you are handy with a welder), then you just throw it in the back.