Speedo Gear Swap Issue (Help)

So I saw a thread on TTora about swapping the trans speedometer gear to fix incorrect readings. The FAQ said that my stock gear was most likely a 30 tooth gear and that I should install a 28 tooth to compensate.

Well I removed my gear and it was totally different than the new one. It only had 17 teeth and I'm a little confused. Has anyone had any experience with this? Any insight would be greatly appreciated.





Here is a link to the original thread.
And pics to show the difference:

 

If anyone cares this mod was done on a 4x4 so I am assuming it will not work for prerunners

 

Did you ever figure this out? I put 31s on my prerunner and it came with 225s so now my speedo/odo is off, but nobody seems to know the gears for a prerunner. All I can find is the 4x4 ones, which are 28 thru 33 i think. The prerunners are 16-20. And there are 4 different 17 teeth gears!