Assembled the seatbacks by trimming off the excess, and loosely attaching the side seat brackets. This was after drilling through the doubler and countersinking the outside seat brackets. Next worked on the seat bottom support by drilling the required holes. One of them was done incorrectly and so a replacement was ordered. on the other one attached the flanges after up drilling. Ended the day by starting on the optional headrests. Located the parts and marked the position for holes to be drilled tomorrow. Too hot to do anything else