I was only opinionating on the gear ratios, not the quality of the trans. My experience with an M-21 was in my 66 Impala with a 396 and a 12-bolt with "highway gears" when I was a kid. It was a horrible combination. At the time I had no clue why first gear was so steep. I though a "Corvette close ratio Muncie" had to be good. I remember I paid $50 for it, with a Hurst shifter. Looking back, it was probably hot.