The rocker shaft assemblies on my 56 f100 consist of a flat washer , a wave washer and then a rocker arm at each end. However , the shop manual indicates a flat washer, a wave washer and a flat washer at each end and then a rocker arm. Indicating that mine was assembled without the second flat washer . I do realize that over the last  54 years these could have been misplaced , lost or modified for some reason . The assemblies are also missing what is referred to as an oil drain tube that returns oil near #1 and # 8 cylinders from the shaft. Is any one familiar with this ? Any help would be greatly appreciated! Thanks Frank