how to check gear ratio

i have a 95 chev 3500 reg cab 350, i marked the drive shaft and tire spu the tire 2 revolutions and the shaft turned 1 complete rev that dont seem right what am i doing wrong

the easyist way is look for the little tin tag on the rear end cover clean it off and see what it said or count the teeth on your gears

There should be numbers on the ring gear also, a bigger number with a dash to smaller that will tell you gear ratio if divided by each other.
You are checking it right too though. Spin the tire two full revolutions and count the revolutions of the driveshaft.

sorry tripple post

sorry dubbel post

You are jacking up one wheel right??

For a example I take a rear axle ratio of 4,0 - 1
4 turns of the driveshaft will give you 1 turn on the Wheels, thats easy ok.
But when one wheel is blocked, the wheel that can rotate free will not make 1 turn but 2 turns.
So now backwards .
The truck is jacked up on one side .
You turn the wheel 2 times and you see one rev on the drive shaft that would make a 4,0-1 ratio.

Remco

Less confusing....... Park with the valve stem on one of your rear wheels straight down..... Next put a zip-tie around your driveshaft with the tail pointing at the ground. Have someone drive the truck forward one complete turn of the wheel while you count the number of times the zip tie comes around.