More info would be helpful.
- What is your trans code.
- Was it just a ratio change or auto to manual change?
- Was the tranny removed?
IDK much about what is in a 2002 but you can do a 5th gear ratio change on some dub without removing the tranny.
With the problem you are having, I would certainly do a proper linkage adjustment. I would try disconnecting the cables and try engaging 5th with the lever on the tranny.
Before disconnecting the cables, have someone shift through the gears and watch the lever on the tranny and you should be able to figure out how to get the tranny in 5th. Basically, 5th will be either all the way up or all the way down and the lever rotated in the same direction as 1st and third.
If you can get it in 5th at the tranny but not with the shift lever in the cabin then your linkage is out of adjustment.