My transmission shifts well but has starting whining. The pitch changes with the speed of the truck. Fluid is full. Not sure how long ago filter was changed if ever. Current mileage 200000. Any suggestion on what this could be. Could a fluid and filter change help or is this more serious.

 

You sure its the tranny? Thought mine was whining too. Upon closer inspection found it was coming from the alternator. It's actually quieted down in recent months. Come to think of it, haven't even noticed it lately...

 

Pretty sure this is the transmission because this only happens with the truck moving and is affected by shift, speed, etc. I will check to make sure and thanks for the suggestion.