This is what I aome up with for my frame reinforcements. I am going to fab up these small "H" sections to weld inside the joints.


I will grind a 1/4" relief into each tube section to allow the welds to be below surface to eliminate the need to grind them.


I will weld the H inside the tube as best I can before assembling the joint for tacking and final welding.

Final welding will fill in the "slot" so a little bit of clean-up with a grinder will smooth it off...

Mark