Chevy Aluminum Powerglide 1.58 Ratio Extreme Planetary Kit 1.58 Ratio with OE length shaft• Ratio: 1.58• Flange Tooth Count: 24• Gear Process Level: Extreme• Material: HY-Tuf Rolled Spline Shaft Length Option: OE Engine power and RPM continue to increase, creating the need for different transmission and axle ratios to get the car down the track as quickly as possible. 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 adurability and higher levels of performance. These units are fully assembled and ready to install. 1 Cryogenic tempering to ultra-low temperatures (-350°F) for an even denser, more uniform gear with a tough and wear-resistant structure.2 Shot peening for increased gear resistance to fatigue failure, cracking or galling.3 Super-finish to reduce friction, vibration, noise and wear on the gear, potentially tripling the life of the part. The 1.58 assembly's front and rear sun gears undergo an additional Dry Film Lubricant (DFL) treatment to reduce spalling and improve longevity. The carrier also includes high strength steel/bronze/PTFE-coated rear sun gear washer and pinion thrust washers.• High-strength HY-Tuf output shaft with “rolled splines” to prevent spline twist• Direct replacement, requires no special assembly or case modification• Sonnax Extreme 9310 Advanced Process gears• Bolt together carrier for ease of service • High capacity reverse clutch assembly includedSonnax's 1.58 is not just the lowest numerical Powerglide ratio...it is the highest quality Powerglide gear we have ever seen!"