If you don't think a truck frame flexes, watch a semi take off from a red light. I have been working on semi frames for 45 years. When I stretch a frame, I cut the web at an angle and weld it. Then I bolt a glove over it with flange bolts and possibly inside also, depending on the application. The more you weld a frame, the easier it will break a weld. If you box it in one spot, it will put more stress on other places. If you look at semi frames, they were bolted with 5/8 flange bolts until the mid 90's and then Huck bolted with 5/8 Huck bolts. Since a Huck puller to pull 5/8 grade 8 Hucks costs around $50,000, I still use flange bolts.
