Really nice 3-view...thanks! And Pat's rendition looks terrific.

The pre-war Chief had a different rudder, much like the "K" and "L" (maybe the same), and the cowl was different; many of them, but I think not all of them, had a joy stick and were sometimes called "stick Chiefs". Even among pre-war Chiefs there were differences in the windscreen, and some had rear windows and some didn't. That's about all I know. Here are some pics that I got from various internet sources...