This vehicle is having some transmission/shifting issues. Don’t know if it is worth paying to have it fixed. It seems to “bang”into whichever gear as it is accelerating. Fluid is full and clean.
Is it worth paying to have it fixed, the response here: https://www.freeautomechanic.com/mechanic/forum/2019/03/transmission-shifting-issues-1995-dodge-3500-van will pertain to this one as well.
You may want to have the vehicle scanned for any existing transmission codes. This will will take you to the exact source of the issue. It may be as simple as a speed sensor not sending the right signals.