Not all NP 273 F Transfer Cases are the same!!
Just learned a tough lesson. Lost my transfer case on my F350 4X4 w/5 speed manual tranny. Bought a clean New Process 273 F from salvage yard. Both had 2.72 ratio.
Tried installing and found after about 45 minutes of trying to stab the output shaft that the transfer case female splines were a tad smaller diameter and fewer teeth than my tranny male output shaft.
Just caution folks that all NP 273F transfer cases within the same model year does not automatically make them interchangable.
Hoipe this saves someone my stress.