1998 dodge ram 2500 diesel shifting in-out of OD on freeway. Now all gears

Hello, I appreciate all the work you've done. Have you consulted a professional technician who is equipped with all the relevant diagnostic tools and equipment and workshop manuals, not to mention first hand experience who could resolve your concern? Use this link to find some shops near you that can help with your concern: www.repairpal.com/repair-shops