I have 250,000 miles on my 1998 12V Cummins with an NV4500 trans. It’s always been a bear to get it to shift into reverse but 5th gear was never an issue until recently when I was cruising in 5th and could not pull it out of gear no matter what I did with the throttle or clutch. I ended up having to limp it home in 5th, which included smoking the hell outta the clutch at an intersection. It smelled like burnt clutch for 3 days!

Anyway, I can pull it out of gear with a screwdriver, once the shifter is removed. Then it shifts through all the gears smoothly but then sticks in 5th again. And again.

Here’s a brief history of the last 5,000 miles:

1. Bought the truck at 200,000 miles. Clutch slips badly. Took it to Clutch Mart in Sacramento. (Too busy with work to do it myself, huge leap of faith to have someone else work in my stuff.) I brought an oversized SouthBend clutch for them to install.

2. The input shaft was sloppy so I had them outsource a “rebuild” to a local shop.

3. Got truck back. LOTS of vibration and surging when releasing the clutch. Got a second SouthBend clutch installed.

4. Got truck back. Still quite a bit of surging when releasing the clutch. Trans still hates going into reverse. Trans pops out of 5th when letting off the throttle. Took it back.

5. Got truck back. Still hates going into reverse. 5th gear seems to work fine. Still surges when releasing the clutch.

-5000 miles of driving-

6. Noticed a metallic “snag” when shifting out of 5th.
Then, it won’t come out of 5th no matter how I play with the clutch and shifter.

7. I remove the shifter and notice nasty rust colored fluid with no odor. I previously bought the expensive gl4 stuff but not sure if the trans shop used it.

8. Trans shifts out of 5th with a small pry bar and medium force. Shifts into reverse quite easily! WTH?

I have read about failing springs, the 5th gear nut backing off, synchros being installed backwards, bent forks, etc. It seems to me that I might lost a spring since now it shifts into reverse without trouble but stays in 5th. It’s only a 2wd so dropping the trans isn’t a huge problem but I don’t want to if I can avoid it.

what could be causing this issue?