John,
I will bite--what's the purpose of notching the end of a boxing plate? Won't reduce stress line if it is attached at the same verticle line on the frame, will it?
Same kind of question on the groove and fillet weld, which looks like you took the boxing plate and inset it inside the "C" of the frame--why? Looks very nice, but is there any other purpose to it?
The notch allows for flexing in the boxing plate. Without it you can experience cracking at the toe of the fillet weld at the frame where the boxing plate attaches. I worked at a welding / fab. shop that spent copious amounts of money analyzing a cracking issue, the notch solved the problem.
Insetting the plates ensures that you don't grind the attachment weld away and it allows room for gas and brake lines, and they are somewhat protected.
