So I have a 76 Duster that originally had a slant 6, 3 speed manual, and 7 1/4 rear end. I put in a sb 360, 4 speed manual, and 8 3/4(3.73 posi). After breaking in the new engine i went to test drive it and when i take off the car violently shakes while releasing the clutch. Once the clutch is...