Lepelletier is a gearset ratio calculator for Lepelletier 6-speed tranmissions.
By default it calculates ratios for ZF 6HP/Ford R6 and Aisin AWTF-80 SC transmissions.
The source code is available for C and Python.
https://www.mathworks.com/help/physmod/sdl/ref/6speedlepelletier.html