axel nut problem

[mjjstang]

so I bought a vlsd becasue I got a decent deal on it, came with shafts, well the drivers side shaft is giving me a headache, there is a small nick on the end of it, where the nut goes, so I figured this is my problem, the problem is the nut will only go on a bit, and then get s very tough to turn, so I grind it down just a tad to where it looks nice, nut hand turns very easily now untill about halfway, by halfway I mean total distance, because the nut will go totally on the shaft and even a good amouint past the nick, about quarter of an inch past infact, so I know that now the nick is not the problem, there is something else. because it just wont turn anymore exept with my large breaker bar and much force. I dont want to break anything, and I know I shouldnt have to use this much force, also I switched nuts, to make sure it was not the nut, the other nut wont work on this any better, and the nut from this axel works fine on the other, so I know it is the shaft, do you guys know what is the problem or what I can do to fix it, the guy sounds like he will be a prick and maybe maybe not give me a new one, any suggestions, BESIDES, hlsd, clutch type, etc, Ive heard that before,