Oil tank filler caps

[GaryM2]

I have 3 different oil tank filler caps (part # 62610-52) where the locking screws (part # 62620-52) all look a little different. Which one is correct?

This is for my 1957 Sportster oil tank (part # 62507-56A)

The third cover has a faint circle in the center of the locking screw. Hard to see in the pic. It may have been chromed over?

Thoughts?

[strong56KH]

The first year Sportster had the same locking screw as the K-model, longer tabs that reach to edge of cap. The margin was smooth, not knurled like earlier K-model, pre 1956.

[dlark]

So 55 would still be knurled?

[strong56KH]

I don't have a close-up of the 1955 KH factory photo, but in the "Legend Begins" it looks like it is smooth.The two 55 KH's in the gallery section look to have smooth caps as well. However, the 1956 Elvis bike at the HD museum has a knurled cap, but it was apparently restored at some point by the second owner before the factory purchased it. The illustrations in the 1955 ads show a knurled cap, but I think those are retouched ones of an earlier model. The factory obviously went away from the knurled version at some point, maybe because it was cheaper to produce? Perhaps in late 1954, if we get a closer look at the 55 KH factory photo. Does anyone have that photo and could it be added to the literature section?

[GaryM2]

How about the gaskets? I see cork and rubber on different oil caps.

What's your preference?

[EKHKHK56]

I wouldn't use the Elvis bike to reference anything. It doesn't even have silver cylinders!

[ambike]

Elvis knew the score / saw the future. Checked out before Hollywood had him " riding " a KK .