subframe connectors questions

i had some small scrap pieces of .083 2X3 that i tacked together to make a mock up of what i want to do. how you tie it together at the front end is pretty self explanitory, so i will show a majority of my pix at the back end. i think i am going to buy some .125" thick 2X3 tubing to actually make the connectors i will be welding in. got pix cant figure out how to post them

heres pix
matt