The Stovebolt Site Forums The Shop Area Driveline Removing 3speed from my 1950?

You can put the jack about anywhere on the torque tube. You'll need to jack it up high enough to be able to move the transmission back to disengage it from the clutch. You may have to lower it down to do that if you can't get it high enough. If you have a crossmember at the back of the transmission (not all trucks do,) that may have to be removed to give you enough room. See attached pic. One option would be to use a ratchet strap hooked over the top of the frame rails and under the torque tube as a sling to hold it up. If you take the weight off the rear tires (by lifting the frame) then there will just be the weight of the torque tube to make it drop instead of the leverage of the weight of the rear of the truck (the pivot point for the axle is forward of the contact point of the tires so pressure on the wheels makes the torque tube pivot downward.)

[on edit] Maybe before pulling the tranny, pull the side cover off and check the interlock between the shift levers. Could be that broke and is restricting the movement of the forward lever. If that's messed up, maybe just repairing/replacing the side cover can fix the problem.