Frame tube jig. Centered between the body mount. Used the body mount to get them close then squared them off the front leaf spring hanger to confirm. Debated using a hole saw but went with a torch for 3 of the 4 holes. Torched the outside frame rail first on passenger and drive side. The inside rail would prevent the torch from catching something on fire while i was on the other side of the frame. Hole saw with a right angle drill was used pass insid frame rail since it is right by the gas line.