Samurai Body

[MY]

This is a very effective way to fix under door smashed bodies. While also installing Old School rock sliders to prevent this from happening again.

Make a hole in front
Make 1.5" bar that has 1/2" holes spaced every 6-8". Weld a 7/16-20 grade 8 nut on back of the hole.
Shove this bar inside the damaged under door box. Make 4"x4" angle iron  rock sliders.

Drill corresponding holes. Use grade 8 bolts and clamp together. Remove one bolt, cut off head, get bolt back into hole below surface of rock slider. Weld in. Weld support pieces from frame to sliders.