'95 tracker, need economic differential

[stickpony]

I have a 5 speed '95 geo tracker with the 5.12:1 differential. I drive long highway distance, and i was told there is a 4.3:1 differential i can swap in from an auto tranny tracker or other such car. can anyone tell me exactly what is available and how to find it in the junkyards, parts stores, etc? what c=vehicles have the 4.3:1 differential besides certain auto tranny trackers, and how do i identify what gearing a car has without having to tear it apart and count teeth?
my email is stickpony@gmail.com. thanks in advance for the help

[CodyJ]

I am also looking for a more broad gearing... I would like to drop my RPM's on the highway to at least do 65 @ 2,800 or make my 5th gear taller somehow!