I have a 2001 Ram 1500 van it is a unibody design.
I knew the 60's Dodge Vans were unibodies but thought they went to body on frame with the new design in about 72.
Have all the vans always been unibodies or did they go back to the unibody in the redesign for 98 - 2003?

The 4106 Greyhound bus was a unibody powered by an 8v71 Detroit so a unibody was proven buss chassis since the 50's.

 

From 94-03 they are unibody from what I could tell. Not sure betwix 72 and 93.

 

Made a trip to picknpull.
All dodge vans have been unibodies, based on observation of a 72, 78, 93, 96 and the one I own a 2001.
Too bad they chose to eliminate the vent windows and make smaller doors on the 98 revision.

 

Our vans are actually have hybrid frames. We have both frame rails and welded body structure (Unibody)

 

Well, the DODGE service manual refers to the van as a unibody. Probably because, although there is a stub chassis in the front it is essentially an engine cradle, that merges into U-shaped frame rails spot welded to the body cage when it meets the body. It is not a unibody like our 73 Dodge Dart but more like a 73 chevy nova with a frame stub/engine cradle merged into the rest of the chassis.
A body on frame is like our old ford f350, heavy frame with rubber biscuits isolating the frame from the body, or any other real truck for that matter.