anyone know how to read rearend tag??
 

How do i go about and finding out what gearing i have in the rearend of my truck? does anyone know how to read the tags? I believe i have a 411 seems to be torqued low

To my knowledge there are two ways as far as tags to tell. Folks will tell you all kinds of ways to mark your tires and the ground and count rotations of axle vs tires and yada yada yada. To me it ws easiest to just look at the tags and look at these charts.

First link-Go to your truck and look at the rear diff from the rear. There should be a tag bolted to it. There will be alphanumeric codes on it. Compare your code to the chart and see which it says. This link is compliments of Cuda_Jim.
Ford Rear Axle Assembly Identification - Page 10 - FORDification.com

Second, you can look in your driver's door jam at the white tag. the bottom lines will have a part that says "axle". Under the word axle there will be either a letter and number or two digit number. Compare it to the following compliments of diesel_brad of PSN.
39= 3.55
49= 3.55
69= 3.55

B9= 3.55 LS
C9= 3.55 LS
H4= 3.55 LS
H9= 3.55 LS

25= 4.10
35= 4.10
45= 4.10
65= 4.10

B5= 4.10 LS
C5= 4.10 LS
D5= 4.10 LS
F5= 4.10 LS
H5= 4.10 LS
Should you have opposing codes between the door and diff cover, go with the diff cover or do the mark and spin thing to verify. The door tag will only be accurate if the diff has not been changed. Like in parts truck I have a code on the door for 3.55 LS but the diff tag says 3.55 open diff.

Also, if you have near stock size tires or even slightly larger you can tell by rpms at 75 mph. 4.10s will have you right at 2500 rpms with an auto tranny and slightly higher with 5 speed. 3.55s will have you closer to 22-2300 IIRC with auto and again higher with 5 speed.

Hope that helps.

Very good info Jacob. Auto rpms with 3.55's are a little less than that (I think mine is about 2100).

Even better! Not my info. Just the messenger...

If you can read the numbers on the tag.

Bottom line of numbers will start with .10 or .55.
That would show an open rear axle with 4.10 gears or 3.55 gears.

If you see L10 or L55, then you would have a traction lock limited slip, again 4.10 ratio or 3.55.

The 4 or 3 is actually under the bolt head.

The next set of numbers would be 10.2 which would indicate it has a 10.25" ring gear.

Top row and the last set on the bottom row are build numbers which I can not tell you what they all mean off the top of my head.

Ford Rear Axle Assembly Identification - Page 13 - FORDification.com
rear end tags

Will Ferrel is probably the worst not funny "comedian" ever