The 5th gear is not in the transfer case.
I'm assuiming your Sport is a 5 speed?
Sounds like you need a rebuilt tranny...
The manual T case and electric shift t case are a little differerent, they will not bolt up, if thats what you are asking. I mean lots of people ditch the electric shift in favor of a manual t case, but it requires cutting a hole in the floor for the shifter and removal of theold electric shift equipment.
The T case has no gears in it. Your overdrive is in the tranny, regardless of what tranny you have. Whoever told you that has no idea about these truck's....
Hope that helps!
Now you can do a search of these forums for "No 5th gear" and that will point you to your real problem.....