I will be pulling a 10500 lb trailer cross-country with a 97 dodge 3500 CTD with the 5 speed. I am wondering if all of the 5th gear driving I will be doing is going to make the nut spin back on the shaft?? The reason I ask is that I will be borrowing it from sombody.

I am by no means an expert, but You might do good to ask him if he has had work done on it. Most of the time, the updated parts have been used on any repair to remedy this problem. A friend of mine had a 95 I believe and they had this problem, but only after many miles. I have ready up on this problem extensively when I was doing the NV4500 swap in my Jeep and because I used to work at a Chevy dealer (chevy's also used the NV4500). It seems to be hit or miss. As far as this one trip causing the problem. I doubt it. It would have been a while coming if it does happen, but it is hard to say that it won't because it is not a new truck. I do understand your concern though. Hopefully, someone else here has better info to chime in with as mine prob was not exactly what you were looking for.

Like was stated previously, it doesn't just happen instantly it will be awhile in the making. But if it goes it isn't that hard to fix. The most expensive part of it would be the fluid. You can't worry about it going, I've seen trucks with under 10K on the clock with the nut backed off, and seen them with over 300K and never been touched. It's a crap shoot is all.

Forget the dodge hook up the Dmax! lol