I did the three tank trick on mine. 88 v3500 crew from air force. I to was sick of passing up goood prices on fuel. came with the dual 20's. i put the 32 gal from a diesel suburban in,for 72 total. I put it in with the box on and without major mods. the rear lip of the tank sat on the front edge of my reciever hitch.with the reciever hitch (10000) there i felt no worries cutting the cross piece out. I bolted a piece of angle at the front of tank for the strap bolts. the rear strap ends were fastened with three 1/4 screws each. No exhaust mods,no shock moving,no welding.I should have trimmed a little where the filler hose comes out from under the box,as it was a slow fillup. the subs and blazers have a sheet metal bump right there. remember, the diesel subs/blazers had dual exhaust and same shock setup also.