Re-looking at the original question "Who makes the pop-top," I get the impression you're looking for the top cap to add to a van you have - or intend to get?

The "classic" roof elevation was from "Turtle Top," but they apparently don't "sell retail." You might find something at Turtle Top Specialty Vehicle Manufacturer Parts Catalog, but they won't let you look unless you log in. I didn't look at what their requirements are for getting logged in.

Once you cut the top off a standard van, you've lost a lot of the stiffness of the entire body. You've got to do a pretty professional job installing the "raised" roof to get any structural integrity back, so it's not really a job for the typical "back yard mechanic." A good body shop could handle it, and they likely would go to Turtle for parts. It's not a "slap on and glue" job, if you want something that will stay together. (Like if you happen to roll it off the road?)

If you're really wanting a do-it-yourself job, you go to the salvage yard and get a similar "hull" that you can cut some panels out of to patch the gap you get when you raise the roof - and re-use the roof you cut off. (Looking funny is probably an advantage, so things don't have to fit perfectly?)

John