cema93

Hey so I bought my current mustang a couple months ago and was wondering if there is a way to tell if it had aftermarket gears? (3.73 4.10) I know that u can open the thing up and see but is there any other way?

JDWalton

use a GPS to get your speed. Then record what gear your in at what speed and what engine RPM. then do a bunch of math using that and your tire diameter.

jz

Or you could just jack up the rear end, and rotate the driveshaft and compare the roations between the driveshaft and wheels.

Roy_R

There is a sticker on the diff....

moosestang

Jack up the rear, mark the drive shaft, mark the rear tire, have someone turn the tire 1 full rotation and count how many times the drive shaft rotates. 3.55 rotations of the drive shaft for 1 full tire rotation = 3.55 gears. So 4.10's would be 4.10 rotations of the driveshaft.

BodyInkMustang

i've always wondered about that. nice info guys!

05 Mustang

+1...

cema93

Thanks moosestang!!! I completely forgot about that. That's pretty smart lol

stangit9090

Next time read the original post before making your post. ****.

Just post what RPM you are at @ 70 mph. Easiest way. No jacking the car up N jazz.

07BLACKGT

OP never said he didn't have a sticker... he didn't even say if he's looked under the car?

The sticker is the easiest way to tell. Get under the rear of the car and there should be a sticker on the lower part of the diff. If for whatever reason there is not, take Moosestang's advice.