Oldspowered67 makes agood point. And that is that everything has to work together. If the front and rear are not securely connected in the middle, its a lost battle. Boxing is the most common aproach, but this can become a mistake. Ladder style frames will ALWAYS flex. Yes, we can reduce the flex, but going all out and welding 100% us a mistake. If we know that it is going to flex, and you stop the rail from twisting, then it WILL eventually CRACK at the crossmembers. So here is what I recomend. MEASURE the inside height of your frame. It should be 5 3/4" or so. Have a steel shop bend up some C rails for you, 5 3/4' (or insert your rail height here) x 2 1/2" wide, by 6 feet long. Once you get these home, cut them to fit into your chassis. Leave about a 1" gap from each crossmember, and span as far forward and rearward as you can. If you are using a bottom mount trans crossmember, good, but be smart and weld the nuts in place before boxing. Fit your boxing C rails in the chassis about 1 1/2", so that you are also making the frame an inch wider, as well as boxing it. put a one inch long weld about every 4 inches, thats all. This will cover the straight middle section of the chassis. Crap, I forgot to tell you, MAKE SURE that you truck is blocked up amd measured to be SQUARE and LEVEL. Take your time, there's no turning back. Next, get about 40 feet of 1 1/2' x .120 wall tubing. Its time to make triangles. Triangles are strong, squares are week, look at the pyramids, still here. Starting at the front cab mounts, on the inside of the frame, fit a tube from the boxing plate diagonaly back to the crossmember on the other side. Fit the tube to the crossmember, not the frame rail. Repeat on the other side, and cut and notch to fit the first tube. This will make an X above the back of the trans. The tops of the tubes should be close to the top of the rails. From the back side of that crossmember, make a second X to reach back as far as you can. Some trucks will a extra crossmember in the middle, passing your X through this is better than making a third X. I try to get the rear of the second X to be inboard of the rear suspension mounts, since thats where all the acceleration load is. But the farther back the better. You can do this for a few hundred bucks, and you will feel the difference. And thats all I have to say about that. Have a great Labor Day Weekend. Cheers.
