Hello Ken,
I had chance to see C-119s then both the dome-shaped Argosy in Coventry's museum and the other type in Cosford's, and I confirm your supposition.
The bottom part of the C-119J tail (visible from the inside in the picture that I linked) opened rising inwards, like the rearmost section of a CH-46 helicopter's ramp. Then the whole tail 'cone' turned up no more than 15-20 degrees, enough to load vehicles or long and cumbersome loads, and even to allow in-flight load drops. Unluckily, once open the tail generated such a turbulence that the tailplanes tended towards loosing control. Thi