This is an M20 wide ratio or M21 close ratio Muncie 4 speed, YOU CHOOSE. This has a 10 spline input and 27 spline output. All internal components are NEW. Case, tailhousing, midplate, shift cover are the only original parts used, everything else in this unit is NEW. If you need a wide ratio or close ratio Muncie, unit, done in CORRECT Numbers for your 1964 - 1965 or 1966 - 1970 GM car, you won't find a better one. 6 month NON ABUSE warranty on this unit. (SHIFTER SHOWN IS NOT INCLUDED) Shifter is for this display only and is not included with this unit.  Questions? Call our HELP line TOLL FREE 1-877-614-GEAR   Monday thru Sunday 8:00 to 5:00 est (WINTER HOURS NOVEMBER thru MARCH)   Monday thru Thursday 8:00 to 5:00 est  (SUMMER HOURS APRIL thru OCTOBER)