Made a writeup on the 5th gear nut since I can't find one on the internet anywhere. http://mopar.mopar1973man.com/cummins/general/5th-gear/5th-gear.htm

well done i like how organized and easy that was to understand, nice to know that this forum has that info now as-well. not to many people would tare their trainy apart to make a writeup on how to fix it (although i guess it paid off for you seeing as how it was loose) keep up the great work i love stuff like this:thumb1:

The only real way to fix it if you don't like to do it over and over and over and over.............. is to just install the updated main shaft.

Yeah I wish I could afford that. If I could afford that I would send in the whole transmission and tell them to rebuild it. I got to looking at the bolt holes and I notice that bolt that isnt a 10mm 12point is the same thread lol. Guess someone lost one of them. One interesting thing though, you can feel the nut loosen up. I remember the last time I did it 5th gear became very tight. Lately it has loosened up again. By that I mean 5th gear has a lot of play in it, but you tighten the nut and the whole thing is tight again. So that's one way you can tell. I need to do some editing on that page, I have thought of a couple things and want to change a few things. I pretty well threw it together in a hurry because someone needed it. I notice there is absolutely nothing for pics of the whole thing on the net so I want to try and get that page as good as possible so people can get the best info. I will throw in some links to quad4x4 and stuff like that to make it better. If you guys got any more tips to throw in let me know!

just an idea to throw out there but wouldn't u be able to take the shaft a machine shop and get a groove cut for a snap ring ? maybe c clip ?

That does sound like a good idea. There have been so many ideas that it's unreal. Every post about the 5th gear nut has a different idea to fix it. I did hear some good results from just putting a cotter pin in it. They might have got a different nut that would work better, like the ones designed for cotter pins. The thing is just doing it to where it doesn't destroy the shaft. Obviously any welding on it is not a good thing. The fully splined shaft that W&F speaks of is about the only thing that doesn't destroy anything and is a permanent fix.

I might actually think about opening up the rear of my trans when I do my fluid change... Kind of got me bugged...

I don't know how yours is, if it goes into the transfer case or what. There is a small hole where the oil goes through to the tailshaft and not sure where it would go on yours. I took advantage of that since the hole is at the very bottom and it allows you to fill the trans up with the speed sensor than the fill port that I can barely get to.