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**Mbeef61** · 07-19-2019, 05:02 PM

One is tapered seat and one is gasket seat. They cannot be interchanged. I have gasket seat on my 69 heads. You have to look at the thread seat in the heads to determine. If unsure post a pic that may help. Not sure if they switched from one to another for different years. Things get swapped so much on these rigs it’s hard to go by a catalog.

07-19-2019, 05:02 PM	#2
Mbeef61 Senior Member Join Date: Jun 2009 Location: Portland - OR Posts: 242	Re: Correct Spark plugs? One is tapered seat and one is gasket seat. They cannot be interchanged. I have gasket seat on my 69 heads. You have to look at the thread seat in the heads to determine. If unsure post a pic that may help. Not sure if they switched from one to another for different years. Things get swapped so much on these rigs it’s hard to go by a catalog.