Something about the cold last night was not liked by the Getrag in my 92...It was fine when I drove out to my buddy's place, then it sat unplugged in -30 for 3 hours, and on the way back home jumped out of 4th on a downshift twice.
Today it won't take 4th on a downshift at all now, and I have to hold it in until the weight is on the gears on an upshift, if I try to do the same on a downshift, it just grinds, and it seems to have gotten worse in the 10 miles I drove it today
No noises, no warning before this(third grinds once in a while if you hit it just right) and it holds the gear fine once it's engaged on accel and decel. The transmission is approx 2 years and maybe 20K miles old.
Anyone have an idea as to what may have happened? To me, it's acting like a bent/worn shift fork, but, that's not usually something that happens out of the blue. Does the Getrag have a plastic syncro follower like a NP435 does, or does the shift fork contact the syncro directly?

 

The fork is in direct contact.

Guys have had trouble with roll pins falling out of the shift mechanism in the toploader.

 

Hmm....
Loose input shaft could cause popping out of gear. (not enough bearing preload)

Mine didnt really make much more noise, but I did notice it being a little more noisy in neutral.

 

I'm thinking I need to pull the shift tower and see what's going on.
The thing makes no noise at all, shifts great and this was a completely out of the blue, zero warning occurrence. I fired the truck up, left Steph's place, drove a mile, downshifted for the stop sign, everything was fine, went through the gears again, all was well, started slowing down for the rail crossing 1/2 mile later, and that's when it didn't engage 4th on the downshift the first time, slowing down for the 1 lane bridge another mile later it did it again. The rest of the 10 mile drive home it was fine.
Today every time I tried to grab 4th on a downshift it ground and would not engage.
It really feels like a shift fork issue, as where it engages the gear when I do hold it in and get it to stay on an upshift is further down than I seem to be remember being normal.
It isn't engaging 4th and jumping back out, it's not completely engaging it in the first place, if you try to hold it in on a downshift it will just grind.

I really wish I had a few extra thousand bucks kicking around, a T19 and a Ranger-III O/D unit sure would be nice in there.