yes I made internal gusset plates which I am going to box so I can weld on all four sides.

My brain for whatever reason kicked in to "How, and Why" mode.

Mostly because I realized I have always just taken someones word for it that "this is the gusset you need" or just made what seemed reasonable to me.

here is some good info I have found that answers alot of the questions I have

http://www.dsm.com/en_US/html/dep/gussets.htm

http://weldingdesign.com/processes/news/wdf_10914/

http://cemsig.ct.upt.ro/astratan/did...n_examples.pdf