I have finally got my money from gieco from the wreck and I'm ready to start the rebuild. I have found a parts truck but need some help. How can I tell the gear ratio? Is there a Certain stamp on the housing or a digit in the vin number?

1997 F250 4X4

I have called him and he's not sure what the ratio is.

 

I wish for the life of me I could remember where the thread was that had all the specifics, but from memory, when ever I am fussing around under the axle, taking the last digit from the first line and the first two digits from the second line, will give the gear ratio, and keeping an eye open for the "LS" on the last of the second line will indicate that it is limited slip. IIRC, LOL

 

Here you go,

Letter and number is ls, two numbers is open.
http://www.thedieselstop.com/faq/949...e=stjs73br.htm

 

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 21-2200 IIRC with auto and again higher with 5 speed.

Hope that helps.

 

Then there's also this as well:

 

If all the tags are missing, which I've run into before, pull the diff cover and it might be stamped on the ring gear. Roll it around and look for the numbers 4.10, 3.73, 3.55 etc...

 

Do the tire rotation to driveshaft rotation comparison to tell for sure if you need to. See how many driveshaft rotations you have with one full rotation of the tire.

 

Thanks guys. Will do

 

Well I bought my donor truck today. 1993 f350. I have a few questions. On the drivers side of the axle it has a pad welded on the back just on the outside of the spring pad. Is that for a stableizer or what is that for? Also will my rotors and calipers fit from the ttb to the Dana 60?