Anybody have any problems with the bolts falling off their rear endlinks from Racingline. I have had mine on for about 3 months and the darn nuts keep falling off even after I used a air wrench and put them on good and tight. Now I have lost one of the bolts with the bushings

I have tried lock nut and it did not work. Maybe I did not apply it properly but I was thinking of using 2 nuts to keep them on? Also, since I am down one side now any recommendations on what I can use to replace the one set of bushings and the bolt size? Thanks.