The late CJ-3A starter is not shown in the "CJ3A.info/tech/starter. Just tyhe earle and the mid arrangement (Mid 1950). Perhaps in your new book?
Is it possible that in a late, key started CJ 3 (1953) early CJ 3B parts are used?
That page is just showing the two different CJ-3A "kick start" type starters and linkages, not the later key start type. The late CJ-3A key start is different than the early CJ-3B and the M-38 stuff.
From the web-page...
"The third starter is Autolite MCH-6203. This starter is key activated with a solenoid mounted to the top of the starter and is the closed nose type. It uses a 129-tooth flywheel. The 1965 Universal Service Manual states that the third starter was put into production with vehicle serial number 30973 and, on a different page, engine serial number 130859. By adding the prefixes 452-GB1 to the vehicle serial number and 3J to the engine number, the result is vehicle 452-GB1 30973 with engine 3J130859."
Any of the flywheels can accept the 129 tooth ring gear.