Congrats on finding a nice T100. They're getting harder to come by these days.
After years of ownership and reading about T100 axle and gearing codes, the one consistent thing I can tell you is that Toyota was fairly inconsistent in how they labled them. There are some widely accepted rules of thumb in the T100 community when it comes to gearing codes.
*Almost* all 4x4 T100's were geared as follows -
5 speed manual = 4.10's
Automatics = 4.30's
A few '93 & '94 models were offered with 4.70's but they are rather rare.
The optional tire package with 31's was fairly common. The speedo should have been recalibrated but if not we're talking about what, a 3% difference between 235's and 31's...? Not much at all.
If you have a GPS or a cop friend with a radar gun, you should be able to determine if the speedo is accurate.
Here's a few links to further confuse you regarding T100 gear codes -
Brians gear ratios & diff page
Erik B's gear ratios & diff page
Two pages of T100 factory specs -
page one
page two
Hope this helps a little -
