A visit to your local bone yard ought to do the trick for you. I've had 2 different tops on my van in the past 29 years I've had it (one of them twice after having done a body upgrade from the original '75 to the current '90). Finding one that fits is basically a case of finding a conversion van of the same body style and wheel base as your van and then using that top. To remove you need a good screw gun/drill and a long extension cord or extra battery. Remove the plasic strip that is usually covering the screws on the metal/aluminum strip that goes all the way around the top at its base. Then remove all the screws in the metal strip. After that the only thing that holds the tops on is caulking so it may take a little effort to pull it free. Sometimes it is easier to get inside and push up while someone is prying the base of the top away from the roof sheet metal.
To prepare your van for the installation you have a stiff drink or two just to get your courage up and then cut the existing top off a couple of inches above the gutter/drip edge! That's the worst part, but really hard to screw it up. You can follow the drip edge around for three sides and then use the fiberglass top as a template to figure where to cut the front. If you have a van style that doesn't have a drip edge then use the top as a template all the way around. Mark where the top sits on your roof and then cut a couple of inches above it.
Now just apply a good caulk to the inside edge of the top and lowered onto your van. It should be heavy enough to allow it to settle to the point it is suppose to. Reinstall the metal strips as they were before using drywall or other screw with a relatively flat head that will self tap through the roof sheet metal. Don't over tighten! The screws are usually about 8 inches apart so it won't be going anywhere once all the screws are in. Replace the plastic trim in the metal strip to hide the screws.
Climb in and stand up! That is if you are 5'6" or less :<
I spent $100 for the current top that I have and it is strong enough to stand on the roof. They end up crushing most of them at the yards so should be able to get it fairly cheap.
Good luck and let me know if you have any issues......
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BoneHead
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1975 E100....Originally! Now has 1990 Body, E350 suspension, Dually 4:10 rear, Airbags, Full Banks Engineering upgrade including pickup turbo setup, wastegate and 4" exhaust. Soon to have intercooler! Engine, all wiring, all mechanics, dashboard, dog house, firewall, controls, engine tunnel and accesories from 1999 E450 Ambulance.
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