Have you checked with GM parts or ACDelco? Enter find parts an drill down the list or find by VIN number. If you went with some custom starter depending on it's amperage draw then match gauge to draw. The gauge GM built with is what's required. The GM speced 'no load amperage draw by direct drive starter is 45 to 110. The gear reduction , 1 to 3.9, GM specs' call for 125 to 190 amps. Clean your engine area, underside also, it's part of preventative maintenance. Good luck.