Our SB Ford Dampers are all made to the 1963-'69 length. This allows the use of both early and late style dampers in early chassis. All of our SB Ford dampers also have both the three and four bolt pulley patterns. They also have three sets of timing marks to suit all SB engines. If your stock damper is longer than three inches, we make up the difference with a series of spacers. Our standard spacers are made of aluminum and are very inexpensive.