2. After we loosened the two 17mm nuts on the tank straps, the unit was lowered out from under the truck. The outer ring needs to be rotated counter clockwise with a hammer and a brass drift. But, before you start tapping on the ring, blow the tank off to prevent debris from falling in your fuel. Also, be sure to put a few marks on the ring and tank, so you can put it all back together the same way it came out.