Hi new to the forum and thanks for the add. 1991 V3500 crew cab tbi 350, np205, 4L80E. Having trouble with the OD not staying in OD. My observation when the truck is cold or I should say when the trans isn't hot, for a brief second it will shift normal into 4th OD for a short period. Not under a load, flat straight road. But it is short lived and shifts out of OD into 3rd. The trans doesn't slip. The fluid doesn't smell burnt. The fluid is a clean light pink. Trans still feels strong but no OD. What might be the problem? It doesn't sound major. Just drove it 3k miles from Alaska to Oregon that way. Still have to drive it to Vegas. Plan on getting service done before I leave and to see if they can pull a code.