I think it's jack up one rear tire. Mark the drive shaft and turn the tire 2 times around and count the number of times the drive rotated. A little past 3 will be a 3.08. A little past 3 1/2 is 3.55 etc...Good Luck
216.158 MPH 12-Port 302 GMC on 70% 171.0 MPH 302 stock head on gasoline 7 years later
