Wait - now I'm confused. I have never seen a 47-54 model truck with a factory rear crossmember. Maybe I'm confused about what you all are referring to as the "rear crossmember". All of these trucks that I ever worked on had a midships style crossmember that the bellhousing sat on and then the transmission just hung off the bellhousing and had no more mounts aft of that position. My idea of of a 'rear crossmember' is one that mounts to the tailshaft housing of the transmission.
A rear transmission frame crossmember and rear-transmission mount was standard equipment prior to 1954 (allowing
the rear transmission mount that "mounts to the tailshaft housing of the transmission" where the torque-tube cover attached to the transmission).
The 1954 change in the geometry of frame cross-member under the rear of the engine allowed the elimination a rear transmission frame crossmember (on 3-speed and 4-speed, but not with a Hydra-Matic).
