Truck has only 23000 mi. I know the truck will not shift into OD until it warms a little, but lately I noticed that it did not want to shift into 3rd properly until warmed up. It happened a few times when it was 20 to 30 deg F, so I was just blaming it on the weather, but yesterday was 55 deg and it took about 1 1/2 miles before it would shift into 3rd. I left it at about 2100 RPM until it shifted into 3rd. Another mile or so and it shifted into OD. Any ideas?

 

Check the easy stuff first. Get on level ground with E-brake on and truck in Neutral and check trainey fluid level. Low fluid level can cause this issue. Hope this helps.