Your 203 shifter assy has a adjustment hole like the muncie trans..
Put the T/C N
Disconnect the shifter rods from the shifter
Put the lever in the N position. The shifter assy has a 1/4 hole in the side.
Take a 1/4 Drill bit and push it thru the shifter assy and the rods and adjust as needed until the rods will line up with the shifter linkage on the T/C.
If the truck has a body lift you might double check to make sure the shifter handle is not hitting the body when you you try and push the handle all the way forward and pull it all the way back.
Your high lock will be all the way back towards the seat and L lock will be all the way forward.