Axel Ratio Question

[Chris4x4Gill2]

Alright....I did read the FAQ on this but my answer isnt making any sense.

I jacked the rear of the truck off the ground both of the tires were off the ground and this truck has a limited slip differential. Driveshaft is disconnected so I counted the # of times the yoke turned...same thing right?.

one turn of the tire equaled about 1.5 turns of the yoke.

Now I know this cant be right. so do I need to multiply this by 2? that would give me 3.??

Anyone know what the ratio options were and what would be close? maybe 3.07?

There is no tag on the pumpkin, but I have the VIN. Is there a way to verify it with this?

[al's71gmc]

Yeah, it's probably a 308 or 307. I think on a 4wd the rear would be 308 and the front 307, and I'd guess on a 2wd the rear would be 308. Does your truck have fairly high shift points, low hiway rpm(compared to other of our year trucks), and not a lot of low end torque?
Might be a little easier to see if you rotate the tire twice to tell weather it's 308 or 343.

[Longhorn Man]

Why not pop the cover off. The oil os probably 20+ years old anyways.
The VIN won't tell you anything.
You most likely have a 3.07.

[Chris4x4Gill2]

Pulling the cover is the next step but I dont have time right now and needed to know.

From further reading the 3.07 seems to be the common option for one with a 350 auto so I'm failry sure thats what it will be. I'll have to wait till this weekend to verify though.

[Longhorn Man]

this is the standard gear for a small block and an auto.

[Blazer1970]

It sounds like only one tire was turning when you did the test. With one tire turning and one tire stationary you need to turn the tire two revolutions. With both tires turning, you need to turn the tires one revolution.

[bryanw1968]

I just had to do this. Pull the dif cover and count both the ring and pinion gears. Divide them together and that will accurately give you your rear end ratio. Mine was 41 teeth on the ring gear and 11 on the pinion. That = 3.72

Or you could do this....

http://www.csgnetwork.com/gearratcalc.html

Counting teeth is the most accurate way and yah, you're dif oil is probably older than you are

[BarryB]

Hey alot of times G.M. has the tooth count stamped on the ring gear so you don't have to try counting. My 2 cents.

[GREASEMONKEY72]

my guess would be 3.07 to but i still need to pull my cover and change the oil and count the gear but i just thought id say so anyway.......lol

[Longhorn Man]

I should add...standard for small block and auto in a half ton.