Have you read this tech tip? https://www.stovebolt.com/techtips/axles/1%20Ton%20Upgrade/ Part 1 step 3, the ring gear will have (among other numbers) 10:41 stamped on it. The number of gear teeth on pinion and ring gear; with some simple math this is the gear ratio. I don't recall what the pinion has on it for numbers but it may have a serial number matching one on the ring gear or something indicating the matched set.
