Speedo gear

Cool, it's all 73 and newer stuff, the 904 is 73 and the 833 is 85ish. I did a search before I posted and saw the stuff about the eccentric carrier for the gear (basically lets you use diff output gears with the same main gear, cool ! ) but didn't know if the gears were the same from a 904 to 833. I'll have to make sure it's close enough to drive the gear without being so close that it chews them up :) 35 yr old plastic yikes

I was really just worried about the the gear being the correct one. Am I correct in thinking that if the gear fits it will give me the correct speed? Basically is the gear that the speedo gear rides against the same from 904 to 833?