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. To determine which spacer you need, measure the length of your damper (see drawing above) and refer to the chart to see which spacer you need. Our standard spacers are made of aluminum and are very inexpensive. If you have a 5.0L engine running a belt driven blower, we recommend that you use our 81009 Steel Spacer instead of the 81007 aluminum one.