I have a 383 stroker in my 79 installed by PO. I noticed that I have a vibration at 1500 RPM. Nothing awful but noticeable. I assume the 383 is externally balanced. The flexplate has a weight but the balancer appears to be of the neutral type. Question is whether I have an incorrect flexplate or balancer/damper. If this stroker is truly externally balanced then it would be the incorrect harmonic balancer. If it’s internal balance then the flexplate shouldn’t have the weight and it need to be changed Bottom line is balancer and flexplate should match. Opinions on my line of thinking?