any of you have a measurement of the distance between the top of the frame rails and the core support? i've got mine all mocked up, with the sheet metal hanging, good gaps. still need to make mounts for the core support, but one side is sitting on the frame rail and the other has about a 3/8" gap. want to see what others have before making the lower mounts. the old mounts were already cut off when i got this truck, so no going to them for guidance.