I had a Mopar master mechanic install a new 4.10 gear set and SG in an 8 1/4. The rear end has the proper gear oil and the SG additive. Drove the car yesterday and it sounds normal when under acceleration but when you back off the gas it makes a loud whining sound. Will this go away in time, normal, or should I have the mechanic check it out?

My car 74 Duster mild 360/904/3.91 13.44/101.54 Son's car 75 Dart Sport 318/904/4.10 looking for a 360 or 408 2004 Dodge Ram 1500 Laramie 5.7 2010 Dodge Challenger R/T Classic B-5 6 speed 2010 Jeep SRT8 for the little wife