i'm not 100% sure i know what you mean but i think you are talking about this..
you can see in this picture how i didnt stop where it bolts to the body like you did when you cut yours. i kept going cut all the way back and cut the body to. i had to redo the inner most bolt that bolts the subrame to the body and weld a nut inside like the factory was and then boxed it in
p.s. why in the world did you go with a drum brake rearend.