Hello Thackero,
I don't claim any expertise on this, so you may wish to wait for more knowing guidence. Looking at my part books suggests that if you are asking about the bolt (and washer) crudely circled in red in the attachment, The bolt part number is 67-283, 3 required and the washer is 2-2138, 9 required, suggesting that the artist didn't draw the rest of them into the image, and they should be used on the other head bolts as well as one might expect.
Hope this is helpful,
P.S, the preview doesn't show the attachment, so I am not certain it is there until I post.
DJinCA