1994 to end of production in 2003 was essentially the same van. At some point the 4-speed OD automatic became more common, I would want that vs the 3 speed, with today's full prices. The best are 1998 and later, with some chassis improvements with no major body or styling change.
Previous generation, 1979-1993, the dimensions and major body structures were similar, engine and drive train options varied more, with slant sixes, V-6s cut from the small block V8, and both LA and LB engine series (318 to 440 CID) and at least five different transmissions, the parts situation gets more complicated depending on just what it is that you have.
I would stick to 1994 and later, with Magnum engines shared with pickup trucks from the era, and a more limited variety of automatic transmissions installed.
Most of the body from A-pillar back is interchangeable with parts from 1979 on. Chrysler stayed with the same unibody from 1979 to end of production, while GM and Ford scrapped earlier unit construction for body on frame (Ford in 1975, Chevrolet after 1996). Of the three brands, Dodge offers the widest model year range for body parts from beginning to end of production.
Tom Test
Itasca Spirit 29B