121  BALANCER SHELL  FITS RCD BLOWER HUBS-  FOR ENGINES THAT NEED A BLOWER HUB BUT ALSO  NEED A BALANCER  - THIS BECOMES BOTH -  SEE ALL RCD HUBS  SCROLL DOWN -----  

Specifically designed for Extreme Duty Boosted Applications on the Big Block Chevy, 481X or Hemi engines utilizing an RCD Crankshaft Hub, this Damper exceeds SFI 18.1 ratings and is designed specifically for Blower or Turbo Applications WHERE THERE IS NO BLOWER BELT TO DISIPATE THE HARMONICS    . This scribed damper does have 360* timing marks.

•  https://www.alkydigger.net/category/rcd-blower-hubs.html   <------  GO HERE FOR RCD HUBS  
• Outer Diameter: 7″  
• Damper Thickness: 1.60″
• Damper Bolt Hole Pattern: 6 x 3/8″ on 2.782″ CENTER TO CENTER   OR  3.110" OUTSIDE TO OUTSIDE 
• Damper Through Hole Diameter: 2.000″
• Weight: 7  lbs
• Exceeds SFI 18.1 standards and is marked on front with SFI Sticker, and on the rear with SFI number stamped into unit.