How to Check What Gear Ratio
 

I seen somewhere that you can check the rear end gear ratio by turning rear wheels one complete turn while counting the turns of the drive shaft..I don't remember what to do after that..I thought it was on here..also another place shows pics of taking cover off and what numbers to look for..Hope someone can help me.
Thanks!

I do know we've covered this more than once before, don't feel like looking for it tho. If a posi/lsd rear, jack both wheels off the ground and spin the wheels one rotation while counting the driveshaft rotations. If for instance the driveshaft spins approximately 4 times to the wheel's one, you have 4:10 gears.
But if you have an open diff rearend, jack only one wheel off the ground and spin the free wheel 2 rotations (not 1) while counting the number of driveshaft turns.
The ring gear generally has numbers stamped on the end, and you simply divide the small number (pinion gear) into the large number (ring gear). Or, you can count the gears and do the math. If the oil has never been changed, it's a good excuse to pop the cover off take a look around inside.

what he said !
pop the cover then you will know for sure

..Yes Sir that is it..Thanks..How does a 308 work out..how may turns for the wheel and how many for the drive shaft for example?

3.08 turns. The gear ratio is the number of turns. Pretty easy to calculate really! ;)

hmm..easy for you to say..so the drive shaft turns 3 full turns while the wheel turns .08 turn? what ever that is..I thank you sir..

No, with 3.08:1 gears and a posi diff, the driveshaft would turn 3.08 times to the wheels one turn.

Here is a chart which provides your gear ratio by comparing rpm's vs tire size...
Set That Speedo! Part 2
Drive your car at a steady 60 MPH, note your RPM's, measure your tire diameter, and find your gear ratio.