Rob, here is a little info on the HC147, I'm going to guess that Warren's pm has some of this too.
This HC147 is from about 1940 and has the early cab used from 1938 to 1945.
This HC147 is circa 1946 and has the newer cab used from 1945 to 1948. Notice the taller windshields and the larger window in the door.
This is the dashboard of the 1938-45 cab
This is the dashboard of the 1945-48 cab.
If the corners of your windshield are rounded then you have the 126 cab which was used from 1948 to 1950 in the HC series. Other models used it until 1953.
If your hood has 4 vent doors your truck was most likely equipped with a Waukesha 6SRKR flathead 6 cylinder engine. If it has 5 doors it was most likely Cummins diesel powered. Your serial number should be on the left front frame rail behind the front bumper. It will read "147HC6XXX or XXXX.
I got these pictures from Warren except for the last one.