Keith : The Assembly Line Part is considered a "Standard & Utility" (Hardware) Part, Part Number 374043-S, described as a "5/8", Flat, Felt Washer, with an I.D of 0.690', an O.D. of 1.30", and a thickness of 0.125". I have attached a p0icture from part of a page in the 1964.5/ 1965 Electrcal Assembly Manual showing its application.
The Sevice Part (C1AZ-10A717-A) would be similar, and with the identical application, only to both the positive and negative terminal posts.
Hope this helps.
Bob