Small Block Windage Trays

318 and 273s have shorter main caps than 340s and require those washers under the bolts so that the windage tray doesn't hit the rods. I don't know of any difference between the main bolt thread depth and have used the same ones in both 318-360 engines. Besides bore size that's the main difference between 318 and 340s, the main cap and saddle taller n beefier. Small c shape vent is the 340 tray.