Matt, they are aftermarket. I was skeptical 15 yrs ago when an old Puller told me about them and handed me a catalog. I ask him ,,,how good are these parts ? He pointed to his 16 horse solid billet head ,super modified and told me. They are in that engine. Haven't torn it down in 3 seasons. Wish I could remember his name. It was the southern tier pulling club in Geneseo NY.
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