Professional Products 0.35 Inch Thick Spacer for Small Block Ford features SB Ford Dampers that have all been made to the 1963-1969 length. This allows the use of both early and late style dampers in the early chassis. All of the 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 the stock damper is longer than three inches, the difference can be made up with a series of spacers. To determine which spacer is needed, the length of the damper should be measured (see drawing above) and the chart should be referred to see which spacer is needed. The standard spacers are made of aluminum and are very inexpensive. If there is a 5.0 liter engine running a belt driven blower, it is recommended to use the 81009 Steel spacer instead of the 81007 aluminum one.