I have a 1979 Chevy 1/2 ton 4x4 P/U. The frame is cracked around the steering box and I need some tips on how to fix it for good. It was fixed one time before by the previous owner, but it broke again. Any info and pictures will be helpful.
I'm pretty sure you can get the reinforcement kit from 4 Wheel Parts Wholesalers. A tricky kit to install, that's for sure. I say this, because GM strongly cautions against welding anywhere on a 73 - 87 Chassis. Don't believe me? Take a look at any 73 - 87 Chassis, and you will find no bracket or crossmember welded to the frame. Only rivets holding things on. Welds eventually crack, especially welds clost to the edge of the frame. In fact, it even says never to weld near the edge of the frame in my 77 GM Light Duty Truck service manual.
Now the reinforcment kit requires welding to install. Proper care must be given when welding the crack, to insure it doesn't return. You must drill a hole at the starting point of the crack, and the end of the crack, or it will continue to crack even after it's welded.
When welding the plate on, you must not have the voltage too high, or you will penetrate too far, and the frame will crack again on the edge of the weld. Never weld what you can bolt on with grade 8 bolts.
Somebody (not sure who but I can find out) makes a bolt on bracket that bolts into the inside of the frame rail on the side with the box, and then goes and bolts somewhere near that crossmember directly beneath it. Its about $100 though. And so far, so good.. its on a friends 78 3/4ton blazer with about 6"+ of lift, and 33s, and it gets abused pretty good.. all of this guys previous frames cracked right there, so when he built this blazer, he knew to take precautions.. If you're really interested I can get more details/pics..
I own a 1975 chevy that had that same problem & I welded it & reinfoced it & it has held fine & I push snow with it do a bit of coyoyte hunting so it has been stress tested more than once. I also work partime for a welding shop that specializes in lenghtening & shortening truck frames & we have fixed several of these with out a problem. If you have a shop like this in your area youyou may be money ahead to take it there because we usually charge $50.00 to $60.00 to repair this problem & guaruntee it.