How do I identify my rear end?

[MusPuppis]

First, this isnt on a Mustang. Its a 94 F-150.

Im gonna be upgrading my gears soon and I was wondering if anyone knows how to identify the size of the rear-end? I have no idea what my truck has and dont know how to tell. Are there any markings on the pumpkin I can look for?

Sorry for posting this here but the F-150 forums Ive found arent very helpful most of the time.

 

[NKau]

If there isn't an axle code on the door tag, you can do it manually. Jack up the rear of the truck, and make a mark on the side of one tire and on the bottom of the driveshaft. With the tranny in neutral, have someone turn the driveshaft and count the revolutions it takes to turn the wheel over one time; if the driveshaft comes around 3 times to 1 time the wheels turn, you have 3.00's, etc.

 

[bobcatv8]

Your truck most likely has an 8.8 rear. There should be a small metal tag bolted to or between two of the rear diff coverbolts. Hopefully some yahoo has not removed it. If it is there remove the tag by unbolting the bolts holding it on {there usually is a digit or two under a bolt head so don't rip it off} and post back the numbers. Easy to decipher with the tag numbers. It will tell you what size ring gear , ratio and if it is a posi-trac or not.

 

[MusPuppis]

Thanks much, gonna check tomarrow when its daylight out.

 

[HISSIN50]

good advice in this thread. i would use the tag info (or call the dealer and ask) for determining the actual rear-end size. but for the ring and pinion, i would not trust the tags - enough folks swap gears that it is hard to know if someone beat you to the punch (though you know the pedigree of your truck pretty well so there is less of a chance of that)......

good luck bud.