My truck is having trouble shifting into 5th gear. As I take off on the highway everything sounds fine, no trouble shift until 5th. It seems like it hesitates or lags and then try to shift in and gives the truck a hard bump. I have a Quadzilla Xzillaraider 2 on the way, supposed to be here tomorrow. Does anyone know if the problem could be timing and if the Xzillaraider will clear transmission timings up? Thank you

 

Should I ad that everything is stock as for as the engine and drive go. Also at "WOT" it will shift fine into 5th.

 

is this a 5.9 (Gas) or Diesel. I'm just asking because I didn't think they built a 5.9 (gas) in 04