Once the tank was ready, I started on the frame. One of the problems in making the tank fit between the framerails is that the rear crossmember is in the way. This crossmember really doesn't have any other function except to stiffen the rear framerails, so I drilled out the rivets and moved it to the rear of the frame. Start with about a 1/8-inch drill as close to the center as you can get and slowly move up in drill size until the head comes off. Then use a pin punch to knock the rivet out.