fullspeed, I agree, jacking up one wheel and counting the number of driveshaft rotations is the quickest method to accurately determine gear ratios. I've come across too many "online charts" and "door tags" over the years that were too inaccurate to rely on. Obviously, tearing down the rear end and counting the individual ring gear teeth is the most definitive method, but for all practical purposes, jacking up one wheel is the simplest.
To answer your question- Yes, 3.73s were stock gear sizes on some 4Runner models. My wife once owned a '99 v6 2wd auto w/ stock 225/75 (29") tires and 15" factory wheels. It had factory 3.73 gears. Within 2 months of ownership, I upgraded the tires to 275/70s (31") and the wheels to 16" knockoff oem 5 spokes. The vehicle looked 1000x better. We did notice a slight drop in mpgs and acceleration due to the increased weight/size, but within a week, we had grown acustomed to it. Aesthetically, it was well worth it.
FWIW, we sold the vehicle exactly two yrs later for $2K more than we paid for it. I was only out $500 for the tires/wheels (bought them both from a friend) and the only maintenance performed on the vehicle was regular oil changes. It's a real joy to own a vehicle that appreciates rather than depreciates.
