I have seen some where they use the extra long mounting studs for the motor on the front studs of the tank. Some weld them, some use a nut to bolt them together to give you the length to mount the tank.
Twisting the mounting plates help keep the tank from sliding down, or a small screw as AZBill suggested works as well.
I had many photos but lost them when my pc crashed.
Try this... Flip the brackets after drilling two holes in each. Mark the bike with a sharpie were you want the tank to fit. Drill two holes into the frame for each bracket. Use a rivet gun to attach the brackets to the frame...then just bolt down the tank to the bracket using lock washers and nuts! I'm working on my own Occ Chopper stingray now. I scratched my head on this issue too but found this pic. Ill include the website it came from because it helps you install the entire kit. Good luck! - Steve- http://www.livefastmotors.com/pages...gas-motorized-bicycle-plans-installation.html