Per the post you linked from Clair - "Unfortunately, the flywheel ring gear on the 10.5" flywheel is located too far to the rear to engage the starter bendix. I haven't put juice to the starter yet, but it eyeballs like there will be little, if any, mesh between the bendix and ring gear."
Or maybe you are asking why the stock (not the 3.7L) starter wouldn't engage the ring gear?
Per the same post - "Obviously, you'll need a KJ starter as well, as all the other "typical" Mopar starters don't have the same locating ring on the snout, AND they're too deep as well."
