Shifting trouble

It is 6 years old
When did you get the transmission serviced last, what mileage ??

67000 miles, tranny fluid bright red no smell. No engine light either, when I step on it the truck shifts great, just that last gear is having trouble kicking in and it feels like it is having trouble going into O/D

Could be an engine performance issue - engine not putting out as much torque as it should, so you have to step a little deeper into the throttle than normal to get the acceleration level you want. But the trans shift pattern is based on throttle angle and output speed, so if the throttle is higher-than-usual, your shifts will be later-than-usual.

Have your dealer check it for fault codes (engine and trans both). They can also take a ride with you (with a scan tool, monitoring trans current gear, target gear, TCC state, throttle angle, and output speed). They can then see whether it is shifting normally, and whether the throttle and speed signals look OK (or are flaky). If you have no faults, the trans is obeying the shift commands from the TCM, and the throttle and speed signals look OK, then I would see if the engine is making enough power.

I'm having the same issue with my 03. I just noticed it the other day i hope its not too spendy to get fixed! make sure you let me know what u have to do. thanks!