The window rubber i used (from the above web site) was WR63.
This rubber has a 5mm groove (to fit over the glass) and a 3mm groove (to fit over the steel panel)
Am presuming that the glass thickness would be standard (or normal , at least) on all panel van coversions.
The steel thickness varied on my van , due to various previous bodges

But 3 mm worked fine.
Before ordering mine , i did actually remove one window to check all of the sizes (glass thickness and steel thickness) I also checked the difference between the overall glass dimensions and the actual aperture size , cut out of van.....this , obviously determines the webb (as given on website)
The reason i changed my window rubbers in the first place was because the wrong rubbers had previously been fitted. The groove for the glass was too big and didn't seal against the glass properly , even with the insert fitted.
This was why i actually removed the glass to check glass and steel thickness to make sure i got it right.
I would think that the WR63 would fit most vans though. The only window i haven't done yet is the sliding window which seems to have a thicker frame for the rubber to wrap around so am not exactly sure if i have the right rubber for that one.
The special tool (listed on the web site) is critical to be able to fit the inserts.
Is fairly simple to use but does require all of your weight behind it in order to push the tool through the insert groove. As you push it through , it opens the groove and you feed in the insert as you go (through the eye of the tool) Not sure if that makes sense but am sure you will suss it out.
Sorry , not sure what rubbers JK's supply but would imagine it would be the same....?
Covkid... Really not sure about your van as it is a caravelle and so factory fitted rubbers. Different ball game i would think?
Ends are glued together with super glue.....remember the super glue 3 advert from the 70's? You know , when the gymnast bloke glued his rubber excercise thing together...he then started swinging about on it like a monkey......if it was good enough for 'im , it's good enough for my van!!
Good luck!