Smaller booster master cylinder beside a 4 speed Saginaw.
The stock column shift 3 speed transmission does not need a crossmember.
The heavier SM 420 needs rear support.
OP has a torque tube transmission/rearend which calls for that crossmember and torque ball support mount.
I don't know how necessary that tiny rubber pad actually is. I drove a '52 for years, that unbeknownst to me, had no rubber left whatsoever on the mount and I drove it 4,000 miles at 60 miles an hour and never had any issues.
In '54, they changed to a beefier bellhousing/crossmember and eliminated the torque ball support mount and the bolt on crossmember.
If this were my truck, I would not install a crossmember and mount and drive it to see if there are any driveability issues.
