Jim, I love that tank! What year model bike did it come off of?
I think it came off of a 1958 Gilera Giubileo like this one. I picked up a basket case at a garage sale a couple years ago. Frame, forks, tins, head and tail light, wiring harness, tool boxes, shocks, etc. No motor.
The tank is heavy guage steel. Has two petcock outlets at the back of each side. Fits the XS frame pretty well (fits over top motor mount and the tunnel is wide enough for the coils to still fit) and has a cool shape when seen from the top.
Plus, its not like you will see a crap load of bobbers with the same tank.
Jim in Minnesota