• Extra-large size retaining plates lock camshafts together at top dead
  center (TDC) on GM 2.8L 3.0L and 3.6L DOHC engines.
• Three-plate set is used to tighten both sets of cams to prevent them
  from turning while setting timing.
• Prevents valve covers from being installed with the plates in place,
  protecting the engine.
 

• Extra-large size retaining plates lock camshafts together at top dead
  center (TDC) on GM 2.8L 3.0L and 3.6L DOHC engines.
• Three-plate set is used to tighten both sets of cams to prevent them
  from turning while setting timing.
• Prevents valve covers from being installed with the plates in place,
  protecting the engine.