help axle keeps coming out

[SPANKY1960GMC]

Hey all

I have a 1960 gmc k1500 4x4 I think it is original limited slip rear end .The problem is every few years the axle berring gives up and the axle creeps out last time on the freeway at about 60 miles an hour .Thank god no one was hurt .I think because of tire and wind noise I am not hearing trouble until it is to late.Do any of you have a modification or idea what can be done to keep this from happening .Is there something causing berrings to flyapart? should they last I have had truck over thirty years now. I don't abuse this truck but it will spend more time sitting than on the road .

Thanks Spanky