Burbs of the era had "anti-sway" bars installed from the Factory. If you can't locate one of those, then pick up an AD sway bar kit from Jim Carter's etc. Ray Stanley(metalman) put onto my '45 GMC and it is the cat's [censored]. The trailing ends bolt into the axle with no mods. Then the front needs to be adapted to the frame. Ray made some plates up to put on the bottom of the frame horns.

http://oldgmctrucks.infopop.cc/eve/forums/a/tpc/f/237106068/m/2271018851?r=4501002951#4501002951
If you're an OGMC site member, use the link.