I've just fittted one in my van. I got it out another van (not caravelle) which had it factory fitted. My van was a panel van that had already had the hole cut before I bought it. I can confirm what Jay says above. The sliding window doesn't really want to fit in properly. there's still a small gap between the window frame and the body. But it's such a relief to have a window that opens. :*If you are fitting genuine Caravelle sliders into a van they won't fit very well without quite a bit of work. The Caravelle and van are designed slightly different and although the windows will fit in a van they sit proud of the recess and look awful (ie you will have a visible gap between the window frame and panel).
The inner and outer skins on the Caravelle are spot welded together from the factory, on the van they are not and have approx 10mm of sealer between the 2 skins.
To fit them in a van you will need to remove all the sealer from between the inner and outer skins, no easy way just has to be scraped out.
Obviously the hole needs to be cut for the windowI:
The inner and outer skins then need to be fixed to each other, this can be done by welding them or bonding them together. To bond them, just apply bonder between skins, clamp, and leave over night.
Once this is done then dril the holes for the window bolts, trial fit the window and you may then need to dress the skins together to get the window to fit perfectly.
There is another way to do this but it involves cutting away the outer skin and just fitting the window to the inner skin, to be honest is a bodge job (although Steiner will disagree with meI
The normal non sliding windows will fit without doing all this because they are alot thinner and can be pushed into the hole more, plus they have a rubber seal which takes up the gap leaving them looking flush.
If you do a search this topic has been extensively covered and there are pics showing how to cut the holes and bond the skins.