Hey manfighter16,finally fiqured my 1st cross sill out,I had two different sets of sills and they both were wrong years!Got new one from Chevy Duty($25)wtth 9 holes on one side and it went fine. Use set of holes all the way through frame,at about half-way even with frame webbing right behind cab,put the longest bolts through sill(with holes in side toward cab)then wood spacer,then lower hole in frame. Line up 9 holes in sill with 9 holes in front bed plate.Finished.