The 86-92 hardtops have the ability to adjust the windshield for a better fit.

-Loosen bolt or knob on the windshield tabs in the dash.
-Hook the tape measure on top of the windshield about 10" in from the corner and pull straight down under the roll bar to the edge of the tub corner right next to tailgate. This measurement needs to be 75 1/8".
-Move windshield forward or rearward and re-tighten bolt or knob.
-Do the same thing on the other side.
This gets back to OE positioning.

Place the top on the vehicle. -On the 1-piece be sure corner seals at the windshield are per instructions, (seals varied from model to model).
-Drop screws in through the top and tub so top doesn't slide off the vehicle.
-Once the seals are correct at the top of the "A" pillar, center the rear of the top.
-Push from the rear as far forward as possible. (I like to keep pressure on the forward pressure on rear of the top as I tighten down the most rearward bolt on each side. Be sure the rear glass operates correctly.) -Tighten down latches to windshield
-Check doors for fit on the top and shim with washers between tub and top to raise the top, if necessary.
When adjusted tighten down all screws.

-On a 2-piece top, place the rear portion of the top on the tub and drop screws through the top and tub so top will not slide off vehicle.
-Set front cockpit cover in place.
-Latch the rear of the cockpit cover to the top.

Push forward from the rear making sure front door seal and “A” pillar seals are per instructions with the windshield.
Center the rear of the top and again push from the rear forward and tighten down most rearward screw on each side.
Check rear glass for fit.
Latch windshield in place.
Check hard doors for alignment and shim if necessary.

The key to installing the top is to make sure the corner seals at the windshield as per instructions and the top is forward as much as possible.