1 matching pair of 3904391 square port cylinder heads, which were used on 1967 corvettes with the 427 / 435hp engine option. Both of these heads have the identical casting number and casting date: 3904391 and L 20 6, December 20, 1966. There have been no alterations, modifications, or machine work done to the ports. These are a bare pair of matching heads, and a valve job should be done prior to engine assembly. The pictured heads dated D 3 7 have been sold, but the heads you are bidding on are dated L 20 6. New pictures will be added as soon as possible.
We do have other 3904391 bare heads, with various dates, depending on your needs: I 9 6 1 pair.
This product was added to our catalog on Monday 01 November, 2010.