I installed this flexplate on my Chevrolet 454 which is externally balanced and needs flexplate balancing and is vibrating so much it has become unusable. The part was tested to fit my engine. I called the manufacturer, told them about the problem, and asked if they would reimburse me for the $300 installation fee. They informed me that this was not their policy. So I got another flexplate from another manufacturer and paid for a SECOND flexplate installation in my truck. I am extremely disappointed.