Range selector question/problem

FRF-15210b

Ever since I've owned this truck, maybe once a week it would grind from high to low. I figured the syncro was going out. But this week, it started doing something different. When I go to low range, it won't be in any gear at all. I'm physically in fifth gear, but the engine is idling. Then all the sudden the range selector will do it's thing, and the truck will "slam" into fifth gear. Kind of like if you were in fifth at 1500rpm, pushed in the clutch until the engine went to idle, and then popped the clutch back out.

You still think syncro, or could the two issues together point to something else? Thanks.

Edit: When I'm paying attention and catch it, I can move the tranny back to neutral, and move the range selector up and back down, and it will work fine then.

 

I'll check that filter out. The "going into neutral" thing happened after I was up North in the cold. I just got home, and I'm determined to sit on my butt the rest of the day. But I'm going to start digging into it tomorrow. Thanks for the info. As I uncover stuff, I'll report back.

 

"Air module assembly". Yeah, it's on the top right. I plan to pull it from the shifter hole in the cab. I'll take the regulator/filter off at the same time.

Here are all the parts:
Eaton Inforanger

I'd like to rebuild everything at the same time, except changing the syncro. If the rebuilds don't fix the problem, I'll tackle that afterward. If anyone wants to look through there and tell me the kits I need to make this happen, so I can get it all at once and not miss anything, I'd appreciate it. I know you all have lives.

 

No, the shifter is in gear. (fifth) But the whole situation is in neutral. Dropping from sixth to fifth, say I should be at 1500 rpm, but the engine is idling. Picture this - you're in a pickup or a car, and you're in fifth gear going down the interstate. Push in the clutch, put it in second gear, and pop the clutch out. That's what I mean by "slamming" into gear. So my truck is at idle in fifth, and then the range selector finally does it's thing, and you have that dramatic rise in RPM, and it feels like you just slammed on the brakes because the engine is immediately hitting 1500rpm from an idle.

I understand what you're saying. Like blipping the throttle to split a 13-speed.

On mine, the syncro grinding is still happening at the same pace. Once or twice a week, or whatever. Hasn't got any worse. But this thing with the range not going into gear is new this last couple days.