If my memory is serving me correct the" 657" carrier was made before the 742 was, maybe prior to 1962, I have seen on here that they both use the same size pinion gear , seals and pinion bearing, I'm not sure if that is correct or not though
I remember seeing one in a 1957 or 1958 Plymouth Savoy flat head stick shift car that had 3.73 gears in it, I wish now that I had bagged that rascal but I didn't