Ouch that's crazy, there's NO WAY I'm messing with my transmission. LOL, thanks for the info though.
I don't even know where the trans-speedo gear is on my '90 (haven't had to look for it yet fortunately), but I changed the speedo gear a couple of times on a TH350. It was a piece of cake (maybe 10 minutes) on that trans. The gears were available at any Chevy dealer too. It should just be a plastic gear where the end of the speedo cable goes into the trans. For the TH350 it was in its own housing, but like I said, I haven't even looked at the trans end of the Tracker's speedo cable.
Also, there are calculators on the Web that will give you any speedo/gear change due to changing the overall diameter of the tire, but I think it's just inverse of that ratio. That is, increase the tire size by 10%, decrease the speed on the speedo 10% -- could be wrong there.
Post what you decide to go with; I'm gonna need to get rid of my 205s one of these days!