[QUOTE=pizzo;2039570]how does it pull when its in the gears?
sounds like The governor pressure solenoid and governor pressure sensor and Valve body problems. To me but I am no expert on this one.
If not those you have a pressure problem for it not shifting gears.

And if my memory is good I don't think you have a 48re... 2003 is a 47re trans the 48re didn't come out till 2004.5 with the 325 hp engines.

Also you will need to check everything out Grounds and wires too sometime they go crazy if the ground wires are not very good.. grounds are at the batteries and on the drivers fender once that is done take it for a ride see how it is...
once that is done put truck in neutral and parking brake applied and check the fluid again after you replaced it...
hope that helps let us know what you find

* Not true mine is an early 2004 and it came factory with the 48re it was pre-2003 that had the 47re and they started putting the 48re in 2003 and up models

 

2002 5.9 2500 diesel came with either a 46RE or 47RE transmission, 2003 you could have a 46RE, 47RE or a 48RE transmission. 2004 came with a 48RE. This is a old post. So we are not going to get an answer from the person who post it to start with..