hesitates to go into reverse when cold

[speed_demon]

When I first start the truck and put it in reverse it doesn't go right in. It will eventually after about twenty seconds. It goes right into drive. If I drive it twenty feet down the road, stop, then it goes right into reverse. It was a little low on fluid so I did it one better and changed the filter and fluid. It still does it.

Any ideas?

 

[speed_demon]

I just noticed something new. When I put it in reverse cold it makes a small quiet clunk right away but it still takes a long time to clunk into gear and it does it a little harshly.

 

[Bent Bolt]

What year truck, engine size ?