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I know that this is a complete newbie question, but I'm hoping someone knows my gear ratio off the top of their head.

I have a '86 CJ7, with the dana 300 transfer case, AMC 20 in the rear, and the dana in the front, and T5. The axles have been upgraded to Moser 1 peice, and i have aussie lockers.

With that all being said, the guy I got it from never changed the gear ratio, so long question kind of short, does anyone know the stock gear ratio? My speedo gear has gone bad and i need to know which size to get. The tires are 32", and that should be all that is affecting it, right? Any help is greatly appreciated, thanks.
Either 2.73 or 3.31.
Crawl under the rear with a good wire brush.
On the passenger side of the rear where it has been machined flat, start scrubbing rust and what not away.
Find the stamped letter. Look up on this link. http://www.jeeptech.com/axle/amc20.html
But then again, some 86's came with Dana 44's when AMC ran out of the 20's.
http://lh5.google.com/85YellowCJ7/R8WJSMGTuQI/AAAAAAAAA-Y/H4bgJ5F9jyQ/s400/amc20.jpg
In the amount of time you spend wire brushing and net surfing you can jack up the rear end put her in neutral, spin the tires and count the rotations of the driveshaft. Count how many rotations of the DS in two complete rotations of the wheel. (you still get to lay on the garage floor/ground so it will be every bit as much fun as whire brushing your differential.);)
Marking the driveshaft and wheel with chalk help when counting. You spin the wheel and count the driveshaft revolutions. I could be wrong, but I believe with a locker, only 'one' rotation of the wheel is needed for the count. With an open diff, two revolutions of the wheel are needed.