what gear ratio?

I have a 74 CJ-5 and was wondering how I find the gear ratio for the front and rear differiatials?

 

If your lucky there will be a metal tag bolted onto the diff cover and it will have the ratio stamped into it. This is good as long as nobody changed the ratio. The other way is to unbolt the cover and rotate the ring gear to find the no. stamped into it as well as the end of the pinion. Theres always the count the teeth method...

 

Or lift the rear tires off the ground. Put a mark on the tire and a mark on the drive shaft. Put the t-case in neutral. Rotate the driveshaft by hand. Count the number of turns it takes to rotate the tire 1 revolution.

If its 3 1/2 then is 3.53
3 3/4 then its 3.73
Just over 4 its 4.10
4 1/2 than its 4.56
Not quite 5 then its 4.88

 

Note this doesn't work for an open differential. If you turn a rear wheel and the other wheel turns the opposite direction, it's an open differential.

In that case, leave one wheel on the ground and double the number of turns given above.

 

4-1/4 turns is probably 4.27 which is a factory option in 74

 

...and to add to that, the 3.73 was the default ratio for that year I believe.