Here is the decoding of the one I have in our Vintage Camaro Racer. It is not original, but it is a rock crusher. Not only does tyhe shaft have no rings, but the case numbers show it to be one as well. See below:
Casting numbers- patent # 3088336 (‘64 and up Muncie), 3925660 (68/69 Muncie 4 speed), cone # 3857584GM= 1966-1970 passenger car, 27 spline output shaft).
Stamped numbers: P9011C=
P= Muncie 4 sp
9= model year
D= April
11= 11th day
C= rock crusher M-22, 10 tooth input, 27 tooth output shaft.
Vin# 19N650376 1= Chevrolet, 9=1969 model year, N=Norwood, Ohio plant, sequence # 650376.
There was a total of only 4253 M-22 made in all 1969 GM models, of which only 2117 were Camaro, and 101 were Corvette.