I have never had a problem with welding a bracket onto one side only of an axle tube, but then again, all the rearends that I have ever used were from donor cars that had a zillion miles on them already, and had a lot of wear on them. This meant that probably if the axle tube did bend a bit, there was enough slop in all the clearances that a slight bend would go unnoticed. However, if you are concerned, then make your brackets like this 3D model I just created. Make it a full 360 degree bracket, then split it as shown to get it over the axle tube, then tack it back together. Position it correctly, then weld all the way around a full 360 degrees in short "bursts" alternating from side to side as you weld. The thing that causes axle tubes to bend is a lot of welding and concentrated heat on one side of the tube only. With a bracket like this, the heat is equalized all the way around the tube, so bending will be kept to an absolute minimum.---Brian