Craig,
The 1954 Shop Manual mentions lock washers for the u-bolts on the front springs (page 3-13; but, no picture) and shows the thick flat washers under the nuts on the rear springs (Fig. 86; referred-to as lock washers on page 4-56). My guess is that the "lock washers" are the thick flat washers.
The Factory Assembly Manual shows no washers on the rear u-bolt and shows the thick flat washers on the U-bolt for the front springs, only between the shock bracket and the axle (Section 3, Sheet 2.00 - as described by Shoeless). The same Manual shows no washers on the rear spring U-bolts (Section 4, Sheet 1).
The springs on my two 1954 trucks had no split lock washers on any of the U-bolts but had the thick flat washers under all U-bolt nuts, front and rear springs.
I have a variety of U-bolts, original and new. Some new ones had to be replaced because the washers could not fit on them (they were bent wrong).
Tim
