Your 87 came with it. The adjuster is a device that connects the front PB cable to the two, left and right rear wheel parking brake cables that go to the wheel carrier's back side. It only attaches to the cables and a portion of it interfaces with a slot in the car body on one side of the driveshaft tunnel and swings along a flat metal guide that is part of the body on the other side of the tunnel.

The bolt is part of the adjuster device itself. Off hand I think it's 13mm. I't can be difficult to see and reach, the bolt head itself faces the front of the car.

If you live anywhere in Rustville or the car is from anywhere in Rustville it can be rusted together. If you can't verify the adjuster's moving parts are free it's probably a good idea to yank the adjuster out of where its located, free everything up and myself I slather the entire adjuster in bearing grease, thick and heavy worked in between all the moving parts.

That's because one of the functions of the adjuster in addition to fixing the correct amount of "slack" in the PB cable system: is to center and equalize the distribution of force between the two wheel cable assemblies. If the adjuster parts do not all freely move the PB cable force can be unequally applied between the right and left wheels. That will cause unequal wear and sometimes cause one wheel's brake or the other to drag.

All this is a problem that only gets worse for those like me who seldom use the parking/Emergency brakes. Then one day you go to use them and then one of both of them drag after they are released.

Whenever I'm under the car in that area I'll almost always spray a good shot of something like Fluid Film or even white lithium all over the adjuster. My state has annual inspections that include testing the parking brake so I try to keep it working.