The 1924 Essex 6 had a pretty unsatisfactory engine and was a far cry from the potent 4 cylinder engines used from 1919-23. From the photo your car seems to be a pretty early 6. With a 5.6:1 rear end ratio at 45mph you are pushing it! The Essex 4 standard ratio was 4-2/3:1 and it is possible to fit the "pumpkin into an E6 rear end housing but you have to first find one, then grind out the housing flange a bit to get the crown gear to enter. You also have to use the E6 spider gears as the E4 had splined axle shafts while the E6 had just square shafts. If your car is a 1924 with 2-5/8 bore I kind of doubt that the engine has enough power to pull that rear end ration on anything but flat going. As far as I know, you could fit a 28-29 motor, whic are fairly common, and have a much better engine and driveable car.