I'm rebuilding the 42 in my 94 f350 right now. The manual says the clearance between the 5th/reverse synchro and the snap ring should be 0. I dropped the synchro all the way on and it's more like .025.

It also says the reverse gear end play should be .006 to .014. That's about .015 with the synchro seated all the way down.
I am installing all new synchros and while these new ones have a lot better looking teeth on the inside they are the same thickness as the old ones. I'm lost. Why is my clearance here so much? I'm wondering if I'm missing something.

 

ZF makes a snap ring kit that has a range of thicknesses for each snap ring. I don't remember if there is a .025" spread, but you should be able to get a little closer to the 0 spec. You are talking about the synchro hub that presses on the main shaft, correct? As for the endplay, I don't think there is much you can do about that. How does the thrust surface on the main shaft look? When I rebuild my ZF, I found that the reverse gear ate into the 5/R synchro hub and the flange on the main shaft. If everything looks ok, it might not hurt anything since it's only .001" out of tolerance.

 

Thanks for the reply. I was stupid. I was trying to put that gear on the wrong end of the main shaft. It mic'd out perfect on the right end. Go figure. It was a long day.