Spectra Premium GM27 Distributor Unit is designed to Original Equipment (OE) fit, form and function requirements accomplished by leveraging our Original Equipment (OE) engine management systems design expertise Original Equipment (OE) design cap and replacement rotor included for fast installation All units new, no rebuilds or core charges All unit components are computer tested to ensure full functionality Each new distributor is road tested to ensure real world performance and to verify that each design meets our high standards for quality