This is not necessarily a simple answer. The 1920 – 1922 Studebaker Light Six used a standard Morse Timing Chain (p/n 43567) with a 14-tooth accessory shaft sprocket (p/n 43309), a water pump shaft gear (p/n 43365) and a distributor gear (p/n 43873). For 1923 and 1924 the Light Six switched to a Morse Type 45 Timing Chain (p/n 120007) with a 15-tooth accessory shaft sprocket (p/n 120012), a water pump shaft gear (p/n 120010) and a distributor gear (p/n 120013). The water pump shaft gear is what I would call the distributor support housing drive gear and the distributor gear is what I would call the distributor support housing driven gear.
When Studebaker made this change, the pitch of the timing chain changed along with all the sprocket profiles. This forced them to go with a 15-tooth sprocket on the accessory drive which changed that shaft speed slightly. To compensate, they changed the water pump shaft gear (the one that drives the distributor support) and the profile of the distributor gear (which is the distributor support driven gear).
The correct timing chain sprockets are easy to identify as they will have TYPE 45 stamped on them. Also, the accessory drive sprocket is easy to identify just by counting the teeth. The water pump gear is also easy to identify as the earlier part (p/n 43365) has four lobes as viewed from the side, whereas the later part (p/n 120010) has a five-lobe side profile. The later Type 45 parts are on the left in the photo.
The issue is identifying the correct distributor gear. The p/n 43873 distributor gear was used on the Wagner and Remy 606A distributors. The p/n 120013 distributor gear was used on the Remy 626A and Wagner K97 in years 1923 and 1924 and on the 1925 ER Models. The difference in these two gears is just in profile which is not something you can see. So, you need to be careful to find the correct distributor gear that matches the profile of the driven gear otherwise the two gears will wear out quickly. Even if your car was made before 1923, it may have been changed over at some point.
What may help is that in 1920, 1921 and part of 1922, the oil filler was at the fan support bracket. At some point in 1922, the oil filler was moved next to the distributor which required changes in the “water pump/oil pump/distributor support bracket” and the “distributor support housing”.
For reference, the 1920-early 1922 water pump/oil pump/distributor support bracket was p/n 43572 and the distributor support housing was p/n 45344. There is no provision for an oil filler on these parts so if you find a distributor gear of one of these housings it is likely to be the older version (p/n 43873), that is, unless someone updated it at some point. Late 1922 – 1924 would use a water pump/oil pump/distributor support bracket p/n 45183 with a distributor support housing having p/n 45545. There is a provision for an oil filler on these parts and would most likely have the p/n 120013 gear.
It’s a lot of information, but as I said, it is not a simple answer.
BTW - Studebaker did not offer a 4 cylinder engine beyond 1919 and they were very different engines from the more modern Light Six. I checked the parts manuals and the Light Six did not share a distributor gear with any of the 4 cylinder models, so I'm not sure about the info from Valley Forge.