Very common problem on external hubs, the best way to solve the problem is to go to internal hubs from a later Dana 44 axle. If that is not in the budget the best thing I have seen done is find a bolt the exact length so it would bottom out the same time it tightens. ( you may have to cut to fit) or you can use studs but the nuts still tend to loosen up just not as often, also using star type lock washers help. If all else fails just set up a socket and extension put it in your center console And check them when you stop.