A small amount of leak is normal. This is 50's tech. Replacing the torque tube bushings can be a real pistol. Do the easy things first and see if it works. Here is a rough idea. The propeller shaft (torque tube) has to move in and out a little bit as the rear axle moves up and down during driving. The section between the propeller shaft and the transmission tail housing is the "universal joint ball". There is a knurled ring that holds the seal/packing in place at the propeller shaft end. Seal wear is normal over time. At the transmission tail housing connection, the ball" is sealed but it is designed to allow a small amount of movement. Seal wear is normal over time. I can't remember if the transmission oil first needs to drained but you should read the shop manual. Prepare to make your garage floor nasty. Remove the 4 bolts from the ball end and pull the retaining collar back. Clean off the dirt, grease and remove the surface rust off of the end of the propeller shaft. Loosen the knurled ring. You should now be able to slide the assembly back (direction toward the rear axle). Inspect the ball for wear grooves. If there are grooves (depth?) then it needs to be replaced or repaired. Follow the instructions in the shop manual for seal replacement.
"Adding CFM to a truck will only help at engine speeds you don't want to use." "I found there was nothing to gain beyond 400 CFM."
