Antonm· Premium Member
I too have done extensive research, and own two of them. A fully splined main shaft is the permanent fix. One of my NV4500 12 valves has the band-aid retainer nut (that I installed) and the other has a fully splined main shaft. I'll continue to run the retainer nut on the one that has it until that transmission either fails or needs to come out for another reason.I have done extensive research on this. I own one. I have talked to many people that own them. There is no 100% permanent fix for this. It mostly comes down to the driver. As long as you don't turn up big power and tow heavy or lug it in 5th gear it most likely will be fine. If you do any of that it will eventually come off due to the inferior design of the splines. I have seen these go several hundred thousand miles without problem. Too much back-and-forth stress on the gear causes it to move on the shaft eventually loosening ANYTHING that tries to hold it.