I have on for sale....I think it's an m-21 not sure though....I bought it fully rebuilt with everything new....for a chevy truck I did for a customer....It have a $200.00 Hurst shifter on it...

I ended up with it back when we yanked the engine out and put it in a 70 nova....

This is , by far, the sweetest trans I have ever had... you can shift all 4 forward gears with just a finger on the shifter.... I got it back with hopes to put it in my 57 belair.....but it aint made it any closer to the car in 4 years....