I have one with over 260k that within the next year is going to my daughter. If it's the OD it could be as simple as the temp sensor. Esp in cold weather. When I took my truck up north it sometimes would not go into OD due to extreme cold. I had to cardboard the Rad. to warm truck up.

1990 Black Monty LS Over 300K' 1993 Isuzu Rodeo LS 4x4 46k (yes only 46K!)1989 Honda Transalp 600 Africa twin,