I feel that it is appropriate for me to reply to Fastmark's post for a couple of reasons. For one, I am the anal retentive member responsible for the post that Grizzly refers to about the reproduction tires:

https://board.moparts.org/ubbthread...lyglas-gt-f60-15-tires.html#Post2738415. I apologize for wasting space on the server with my worthless and trivial post, but I thought this was a restoration forum.

Now, about the washer and wing nut. I can't speak for the 6 and 4 barrel engines, but I can say that my original 71 Barracuda with 318 2-barrel had a washer under the wing nut when my father purchased it with 13,000 miles. It was a Chrysler owned rental car before he bought it. Can I say with 100% certainty that the washer wasn't added before it came into our family? Nope. But I can provide a Dodge promotional photo of a 71 Challenger 318 with a washer on the air cleaner.