The Washer,lock Md5/16 is the lowest priced item on this Alternator schematic.
Parts such as the Alternator: Bolt,hex 3/8x3-1/4, Washer,lock Md5/16, Washer Flt Sae 1/2, Bolt,3/8-16x1-3/4" are included in the V8 5.7 Yems 1990 Engine Alternator parts fiche.
With a quantity of two pieces, the Washer,lk Med 3/8" is the most used part in the ALTERNATOR diagram.