Rear differential gears; how to determine.?

I've got a 1993 Formula with an LT1 and the gearing in the rear diff is clearly a lot higher than stock. I'm trying to sell the car and would like to have an idea of what it has for gearing. The speedometer is off; it's 20% over. Can someone figure this one out for me?
Rear differential gears; how to determine.?
the most common one is a 3.73 which is what i would like to put in my formula same year..see if you can answer my question boy i tell you these cars are somthing else when it comes to maintainence
Rear differential gears; how to determine.?
there's no way to figure it without counting the ring gear and the pinion gear teeth,then you divide the lower number in to the higher number,that gives you the gear ratio on it,good luck.