I have a rear axle the id tag reads like this ford axle TAG s806d / 08 -8 -8 -9j12 can anybody tell me what the gear ratio is in this axle???????? or how can i figure out what the ratio is? YEAH I LOOKED FOR THE STICKER NOT THERE NO STICKER ITS SUPPOSED TO BE A 3.55 GEAR REAR AND 3.54 IN THE FRONT BUT THE AXLE ID DOESNT MATCH I NEED TO KNOW WHAT GEAR IS IN THE REAR

 

I dont know how to read the axle tag, but if you get the axle code off the sticker in the drivers side door jam i could.

But im sure someone else will show up who can read the tag.

 

YEAH I LOOKED NOT THERE NO STICKER ITS SUPPOSED TO BE A 3.55 GEAR REAR AND 3.54 IN THE FRONT BUT THE AXLE ID DOESNT MATCH I NEED TO KNOW WHAT GEAR IS IN THE REAR

 

ohh, haha, makes sense. Someone who knows how to read it will show up before long.

But you can always turn the drive shaft and count how may times it take the drive shaft to turn the wheels once.

 

You are missing numbers, remove the bolt holding the tag and post them exactly as shown in 2 seperate lines.

 

An S806D is out of a `87-91 F150 or 1987-91 Bronco U150.
It is a 8.8" rear end with a Ratio of 3.55:1 and it is NL.
The 08 is not right as that would be the end of the ratio and 08 does not go with 3.55:1, it should be 3 and then a space and then a 55. The 3 may be under the bolt head that is holding the tag on.
It was made at the Sterling Plant.
The 9J12 says it was made on the 12 of August 1989.

 

If the tag reads S806D the axle was made for a F 150 Pickup 87-95, E150 Van 87-95, Bronco 87-95. It is a 8.8 In. with a gear ratio of 3.08. It is also a unlocking diff.
Hope this clears anything up.
Ralph theemailgoeshere@yahoo.com

 

On 4x4s there may be a white paper label that is on the passenger side ,back side ,of the front axle support -facing backwards and printed upside down. It will have the ratio of the differential on it and if there is an open or limited slip inside and the date of manufacture. And the ring gear size.In dry climates-this label will still exist. In wetter climates-it may have disappeared by now. My label is still new looking my 92 4x4.

The axle label is printed upside down because apparently these frames were assembled upside down before being mated to the cab/box. It is easier to drop the axles onto the frame when the frame is upside down and bolt everything together.

I used this label when looking at used Fseries on dealer lots-it was easy to find out the differential ratio and if limited slip without the salesman having to unlock the door to the truck.

But it seems that the previous poster nailed it what ratio you have on your truck.