I would certainly expect that it is not "factory"... I assume it is one of the "Webasto" sunroofs, which are admittedly cool, and certainly a totally period modification. They are usually seen on the likes of VWs, Jags, MGBGT, etc. I've only seen 'em factory on perhaps French cars. (Citroen 2CV). And perhaps the VWs.

If you go for it, I sure wouldn't expect it to be leak proof, though I have no personal experience with the myself. There also might be some structural issues when put in a Volvo wagon, but only if you plan to put the car on its roof....

I would think that if it came off a wagon, it could probably be put back on a wagon.

-Matt