I stabbed the shifter back into a T18 tonight. This is on a restoration I'm doing for somebody else so I've never driven this truck before. First gear, shifter has to move forward a lot. Pulls down into second gear fine. But going into third and fourth gear the throw is very short, it feels like the shifter only has to move a few inches. Then taking it over to reverse, the shifter has a long throw forward again.

Also while in gear, the shifter still has quite a bit of side to side play (but not like when it's in neutral).

Is this correct for a T18 or did I not have something lined up well enough when reinstalling the shifter?

 

If you have all the gears they the shifter is installed right other wise you would not be able to put it in any gear.
The T 18, NP435 and T19 are truck transmissions and do have a lot of movement between gear changes but it sound like yours may have a little more than normal.

I forget how the T18 stick goes in and mine is stuck under a bench and cant get to it to check.
But if the stick goes in comes out by pushing down on the retaining ring and 1/4 turn CC and pop it up then there is some hope for a fix IIRC.
There should be 2 pins on the tower the stick slots fit over. Over time they get wider and add play to the throw.
I forget just what the fix is now but you have to get the slots thinner or the pins larger but still able to hold the stick retainer cap.

Also did you remove the tower the stick goes into?
Put the trans in nutral pull the stick and then pull the bolts and tower.
The shift forks should come out with the tower.
On the end of the forks there should be plastic ends that fit into the shifting rings.
If the plastic parts are missing that can also add to play when shifting and in a gear.
That should give you somethings to check.
Dave ----