I am going to use my '74 K5 for some hauling. I figure about 1600 lbs. max. It won't be subject to this kind of load all the time, but I don't want to have to worry about collapsing the suspension when I want to haul a bunch of stuff. I already plan to replace the rear leaf springs with new leaf springs. I am debating what to do next: overload springs, coil springs, or air bags? What's your best advice for this? Also, do I need to worry about breaking the axles? These are the 6 bolt, 1/2 ton axles that the truck came with, how much weight can they bear up to before giving up the ghost?