Yes indeed as Dusty says.
You will discard the existing yoke and rear bearing retainer and seal, but have the speedometer drive gear pressed off the yoke and remove the speedometer driven gear from the rear bearing retainer.
Then find you a rear bearing retainer from a 1948- 1954 1/2 or 3/4 ton sm420, make sure you get the front yoke to go with it. You will need a new Ujoint https://www.fillingstation.com/detail/4114/Chevrolet_19401954_UNIVERSAL_JOINT_REPAIR_KIT.html. You will able to retain the existing rear yoke that you use with your 3 speed that slides into the torque tube.

The torque tube rear bearing retainers are starting to get scarce because everyone has threw them away but they are around. I have sourced at least one vendor that sells a complete new front and rear yoke as well but it is very spendy. https://www.fillingstation.com/detail/4985/Chevrolet_194854PU_4SPEED_UJOINT_ASSEMBLY.html

Good luck,
Steve

Last edited by sstock; 08/13/2019 1:10 PM.
1953 Chevrolet 3100
261 cu inch, sm420, 3.55 rear, torque tube still,omaha orange, still 6 volt, RPO green glass, side carrier spare, all done
In the DITY Gallery
Video of the 261 running

1964 GMC 1000
305 Big Block V6, sm420, the next cab off restoration