had an alt on the car but wouldn't work..got a rebuilt under warrenty and installed..found regulator wasn't working either..replaced with m/p constant voltage reg. and now charges like a bear..but as soon as we installed the new alt,which was tested befi=ore we left the store, it went nuts,,msd said to install a noise filter on the powqer lead for the tach, but someone else said no..thats why i was up in air..lost a meet 1st place because i didn't have time to charge the battery between rounds..hense the alt!!