Try to look at the bottom rear corner of the rear-most side cargo door to be sure of its shape. At one point in time there was a changeover between a sloped shape right in front of the wheel arch to a 90 degree shape.
I'm not an expert on doors, perhaps Nate or Reed are? You may be OK on the rear doors as a set. The metal is likely thinner on the modern van doors. The door frame electrical contact button(s) for the license plate & electrical door locks, if so equipped, may be different.
Part of the issue is 1978 was the magic year when the big body style changeover took place. Depending on when during the year your van was made, it may share more with the 77 and earlier vans, or the 79 and later vans.
-It's been such a LONG TIME... BlueShift>>
1981 Dodge Ram B250 Custom Sportsman Maxi Van
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