Hi; I have a 53 Panel with LS1. I used a tank from Ric's Hotrods in the rear. Brackets on the tank are welded on so they much up with cross member of four link (welded on brackets). Slid the big cross member back and use it to mount the rear of the tank.
My problem is now that there is little room for exhaust to go. The tank has the fuel pump and I have
made a hole in the floor for getting at it. Hope that helps.