Check the threads in the hubs for looseness as well as the condition of the bolt threads. If looseness isn't addressed quickly once it happens, both the male and female threads will wear, and no amount of tightening (or the imaginary benefit of lock tabs) will solve the problem. Recondition the threads in the hub with Heli-Coils, and find a suitable size and length new bolt to minimize any sloppy fit. I believe the proper bolts will have a short, smooth shoulder where the bolts contact the axle flange to prevent any relative movement associated with a threaded area of the bolt working against the flange. A piece of soft aluminum sheet metal and a little work will allow you to fabricate flange gaskets.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!