Available on 1987-89 models. Eventually they will start to leak. The seals will wear down just due to age. There are a few options available, some temporary fixes, some a little more permanent.
Before you spend too long trying to fix the t-top, verify that it's actually the t-top that's leaking. Water often leaks between the window and the door jamb (near the handle), as the Door Hinges sag over time. Us a hose to verify where the water is comming from.
The easiest place to store the t-tops is behind the seats. The intent was that the part with the glass edge facing up, and the locking mechanism resting on the floor. The problem with this is that the floor has a ridge running under the seat, and this causes the metal trim on the t-top to bend. Unless you put some padding down to minimize the ridge you may be better off storing the t-top with the glass edge on the floor.
Believe it or not the t-top also fits inside the frunk, even with the spare still in there. The glass edge is at the top, and fits perfectly into a slight indent in the hood.
Definitely the easiest option. Restore the flexibility of the tired rubber seal and improve it's water-proofing. Use a product with silicone, which will help repel water. Black Magic "Tire Wet" works well. Vaseline also works (although it has a minor odor, and may cause the rubber to deteriorate over a period of years of application).
Build New Layer
Applying a thin layer of silicone sealant is fairly easy, and has the advantage of being undoable if it doesn't work out so well. This works well for leaks at the corners of the t-top on the outside edge of the t-top (on the a-pillar). There are two methods to prevent the adhesive sticking to the rubber on the car side: either use some Vaseline or cling-film between the t-top and the a-pillar. Cling-film is tricky and tends to cure in a 'wrinkly' manner.
- Get hold of some Permatex Black Silicone Adhesive Sealant (available at most auto stores); also get either Vaseline or cling-film.
- Put a good layer of the Vaseline (or cling-film) on the corner of the a-pillar; this will prevent the adhesive sticking whilst it's drying.
- Clean and dry the rubber at the corners of the t-top panel.
- Squeeze a thin layer of Adhesive onto the rubber seal at the corner of the t-top.
- Smooth it out as much as possible -- don't worry too much.
- Now gently place the t-top in position on the car. Do not put too much pressure, and don't close up the t-top. Just let it rest lightly in place. This will cause a good fitting seal, and will tend to smooth out the wrinkles in the adhesive.
- Wait an hour or so, and then slowly lift the t-top up and off. Wait another hour, and the rubber should be pretty solid.
Adjust Locking Mechanism
Also refer to Megaboost for a series of pictures of the entire process.
KBox sells new seals for the a-pillar and c-pillar, but currently does not sell the seal for the t-top itself.