Made 3 aluminum shims, 6061-T6 .032, to go under the ribs where they attach to the spar. There was a gap because of the SD75R1-8 doublers. Riveted the SD75R1-8 doublers to the SD75R2-3 spar with #4 solid rivets. Riveted the 75R2-5 rudder hinge angles to the spar with #5 solid rivets.