New LS1 Owners - Newbie Tech - Help with dual/dual install - how to mount rear tip hangers?

Ive installed an oem dual/dual system on my 2002 SS, but cant figure out how to properly mount the rear tailpipe hangers. The other hangers bolt into the frame, but the rear ones require some engineering to mount up to the large frame holes. If you are familiar with this install, how do you mount the rear hangers?

Ok, did some trial and error. 5/16" bolts and star washers on both sides, use a 1" wide washer to cover the big frame holes, and you can wedge a wrench into an access point in the frame to hold the nut assembly tight while you tighten down on the bolt head.