Here is another interesting piece about muncies The early M22's up to 1970 came out with the 27 spline mainshaft and coarse 10 spline input shaft. They went up to the 26 spline input and 30 spline mainshaft in the big block Chevelles 197?. So practically all the early M22 1st generation Camaro's had the small mainshafts and coarse input shafts.