Review on Upgrade Your GM 12-Bolt Truck Differential with 🔧 USA Standard Gear (ZG GM12T-342) Ring & Pinion Gear Set by Michael Vargas

Overall I'm happy with it, but not without aches and pains. The gear had an unfinished notch under the spline towards the head. Expansion sleeve and seals do not fit. We're talking thousandths of an inch, but you could still see and feel the unfinished lip. So after some grinding and polishing, the bushing and spacers will fit. After four days of adjustment, test drives and good traces of paste, the transmission still whistles, mostly when decelerating, especially in the 40 km/h range. Researching further, I found that most online 4x4 dealerships advertise these gears as "not recommended for use in quiet vehicles". Apparently it's a quality control and finishing process that can make you whine no matter how well you did the setup. Good gear preload (I used a solid spacer), good backmarks, good clearance, torque to spec. You are set up correctly. You only have a little buzz. So my solution was to install a cherry bomb and a resonator. Fixed the yammering issue.