[Chaparralman1974]

I know that this is an old thread, but 1967 was the 1st year that the transfercase in 4WD trucks was married to the transmission and was the only year that the SM420 was married to the Rockwell T-221. 1968 saw the adoption of the SM465 married to the T-221. I believe that combination was available until sometime in 1969 when the NP205 transfercase was introduced.