The mirror must have a wire for the auto dim to turn off when you put the car in reverse. You should go back to the yard, and get the harness from the donor of the mirror. The harness runs down the B pillar and plugs into a connector at the base of the B pillar. You may still have to run a wire to the steering column to activate the turn off when in reverse. It may even require the transmission position switch from the donor car. Some of the transmission position switches have a clamp and screw, and some are just clipped to the column. The ones with the clamp and screw have different, and more connectors than the clip on variety. I would suggest that you look at the wiring diagram for a 94-96 for the proper connections.
If you got the mirror from a 94, it has an adapter harness (about 2 inches long) with a 4 pin, and a 1 pin connector on one end, and a single rectangular one on the other end. The mirror itself is the same as a 95-96 with a long rectangular connector at the back.
You have to remove the inner clips for the visors, the driver's side visor, A pillar, B pillar, both driver's side courtesy lights, and then you have the Velcro strips to separate. The center courtesy light is part of the roof harness.
The Caprice headliners are easier to remove intact. The RM and OCC liners are easy to break at the vista window. I picked up a Caprice headliner, and reinforced the area beside the vista window from the top side with carbon fiber (you could use 6 oz. fiberglass cloth). You could repair a cracked/broken RM or OCC one if you have all of the parts, and can get them aligned. It only took about 6 inches by 2 feet for each side. I then cut out the hole for the vista window, and used the extra material to patch the hole for the courtesy light. I used the original headliner as a template, and cut holes for the side courtesy lights (front and rear seat). I used a Dremel with a 1/8 inch side mill to cut the holes. It took about 10 min. to cut them all.
I had it covered to match my interior.