Has anyone dropped the pan on that truck's transmission and/or air checked the servo at all?
If it only has first gear and speedo/DRAC/VSS/VSSB all work and will not upshift to 2nd even when everything's hooked up/plugged in then the 2-4 band is shot (3-4 pack prob is too). By pulling the plug you're simply testing the 3-4 pack for mechanical function...If nothing happens (i.e. no movement in limp / 3rd and no man 2nd) have your friend pull and rebuild the transmission.
But drop the pan and see what's in there if he hasn't already done so.