Part #: 747600. Powerglide Bolt-Together Planetaries (1.8 Ratio). TCI Bolt-Together Powerglide Planetaries are built with the racer in mind as they optimize both strength and ease of use. It allows for easy rebuilds and gear ratio or output shaft changes without sending the unit back to TCI. Dec 27, 2017 · “If we did a Turbo 400 with OEM gear ratios, we’re probably pretty dollar for dollar with a Powerglide,” Coan said. “I think that works if the person is primarily driving on the street. However, once you get to the track, then the OE ratio becomes an issue.” Gear Ratio Calculator. Ring-and-pinion selection made easy! Save yourself the headache and let us figure out your ring-and-pinion gear ratio! Just type in your info (example: 5000 RPM), press calculate, and you’ll get the right ratio without the guesswork.