Chevy Aluminum Powerglide Transmission Sonnax 1.58 Ratio Extreme Planetary Assembley The innovative Sonnax 1.58 ratio extreme planetary assembly kit 28158G-06 is designed to fit into existing Powerglide cases, allowing racers to achieve the lowest numerical ratio available for the Powerglide without the hassle and expense of converting to a different transmission. Extreme planetary assemblies from Sonnax include advanced process sun gears and pinions made to the same exacting standards used on formula 1, Nascar and other high-end professional racing circuits. Advanced process parts undergo an additional three-step process that allows for greater durability and higher levels of performance. Super-finish to reduce friction, vibration, noise and wear on the gear, potentially tripling the life of the part. The carrier also includes high strength steel/bronze/PTFE-coated rear sun gear washer and pinion thrust washers.