do you have any specific questions? I think there are some idiosyncracies due to the companies which converted the vans to campers holding on to old models for a little while before converting them.
As far as I know, (and I have been wrong in the past!) apart from the PA to PB (front - rear handbrake), most stuff can be swapped across the model changes. There is also a late/early starter motor to worry about (amongst other things) and of course the Dodge facelift.
The other thing is that lots of vans will have been heavily fiddled about with by now so there is a good chance someone has already upgraded your van for you!
cheers
Rupert
"With great cars comes great responsibility"
www.littleyellowcar.co.uk