I just completed a crossmember to adapt a passenger car C-4 into an early Econoline. I used a 65-67 engine crossmember and a 4"X6" gusseted steel plate. On the 61-64 trucks the original transmission hanger must be removed or trimmed, the 65-67 does not. I used the frame mounts from the 65-67 to attach the crossmember to the frame rails. It's very simple to make. Finding an original automatic transmission is becoming difficult. This should make swapping a more common passenger car transmission easy. I am checking to see if it will also fit an AOD.
Fred
Fred