Spark plug,what is it?

[Huckster]

I know there have been many conversations about 3-X spark plugs I,m just a little confused on what i have. I know the one on the left is a newer repro so i didnt take it out of the box but the one on the right has the round top 3 so what is it?

 

[Fred]

I know there have been many conversations about 3-X spark plugs I,m just a little confused on what i have. I know the one on the left is a newer repro so i didnt take it out of the box but the one on the right has the round top 3 so what is it?

That is an after market plug with the correct round top #3.. The base is of the later style knurling.. They were made that way until the Co. went to the flat top 3....If you take notice of the color on it, its more of a deep red, where all, or most originals were more of a orange color..