And to add to Jon G's very good instructions.....on the shifter box that it is on the steering column.....make sure your two levers are parallel with each other, BEFORE you install the shift rods at the top to the two levers coming out of the shift box. These two levers need to stay parallel....this is critical. And they are usually pretty close to horizontal when they are correct also, (which would be pointing towards the engine). You can verify this by taking the grease cap off the shifter box, and when the two levers are parallel, the two shift gates inside the box should be lined up with the shift tab (the tab is what moves up and down inside the box). There is not a lot of gray area on this either....it has to be pretty close to right for it to shift smoothly. You can be off a little and it will shift, but it will hang up more often than not.
On my 51 3100, the adjusters at the top of the shift rods just slide up and down and you tighten a nut when they are at the right position, more or less clamps itself to the shift rod. But on my 48 truck, these adjust just like Jon G says, they are threaded, so you have to screw/unscrew them to get the proper adjustment.
One other thing, you don't need any slack at all, on the inside of the shift box. Take the top cover off, there's 4 screws that hold it on, and you can watch how it works. Very simple design. There is a spring inside, rides on the shaft above the top shift gate, that keeps tension on all of it....not a stout spring but enough to keep everything snug.
Confused yet?
