I modified the top and bottom inside brackets to lie on top of the side brackets. I drilled holes in the center of two brackets and then cut away the center at each end. The ends were then bent to make a joggle so each end would lie on top. The two top and two bottom brackets were drilled to each other and then the oil cooler doubler was clamped to the sides. The doubler was drilled to the two sides and then the doubler was drilled to the top and bottom brackets. The corners of the doubler was drilled thru the side brackets and then the joggled corners of the top and bottom brackets.
The oil cooler mini-plenum
The mini-plenum drilled to the doubler
The underside of the mini-plenum with the corners overlaid
