identifying ford 9" rear end for type of gear lube

[thebannister8]

hi all...i have what appears to me to be a ford 9"...i have axle code 08...3.50-Ford(3300-lb.)...i have a 67 f100, 6 cyl 240...i got some gear lubricant so i can drain and refill my rear end...i got sae 80w-90 gl-5...the applications on the bottle says it can only be used to top off limited slip/ positive traction rear ends...if i have either of those i'll need to get a gear oil specific to that...i'm wondering how i can identify if i have limited slip/positive traction or some other type...i've looked through my manual and multiple web articles on the 9" and the numbers i got off of my rear end don't match anything i've read...these numbers may be wrong (i'll double check later)...do any of these look familiar...thanks

c5an dif ?7a31 ll888 and on the metal plate tag is dmt50788311

[BobbyFord]

hi all...i have what appears to me to be a ford 9"...i have axle code c...3.50 - Ford (3300-lb.) 08...i have a 67 f100, 6 cyl 240...i got some gear lubricant so i can drain and refill my rear end...i got sae 80w-90 gl-5...the applications on the bottle says it can only be used to top off limited slip/ positive traction rear ends...if i have either of those i'll need to get a gear oil specific to that...i'm wondering how i can identify if i have limited slip/positive traction or some other type...i've looked through my manual and multiple web articles on the 9" and the numberrs i got off of my rear end don't match anything i've read...these numbers may be wrong (i'll double check later)...do any of these look familiar...thanks

c5an dif ?7a31 ll888 and on the metal plate tag is dmt50788311

The code you posted (c) doesn't make sense, decode your door tag here...> http://www.fordification.com/tech/VIN67.htm
If it's a 9" and the tag is still there on the diff, it will have a ratio number like, 3.50, if it is limited slip then it will say 3L50. If it is limited slip then you will need a friction modifier additive to add to the 80/90W gear oil.

[thebannister8]

i goofed up on the c part of it...it's code 08 from my door plate...i noticed in the decoding the vin section that there isn't a red asteric by my rear end that would denote it as a Locking (Limited Slip)...limited slip is covered then...is locking the same as positive traction...thanks

[papabug71]

Looks like you have a 3:50 geared open diff. rear end.


A locking differential & limited slip are two different things. To the best of my knowledge, Ford never offered a locking differential in the 9" rear. Only limited slip. (The database is confusing, i know.)

[67mann]

old fashion mash the gas pedal....How many tires are spinnin...then you'll know Both tires....friction modifer/gearoil,One tire...just gear oil. You also can clean the tag(on the rearend itself)of and it should be evident of 9" rear you have....like Bobby said

[thebannister8]

i cleaned off the numbers and took a real good look...where i'm looking is on the driveshaft side of the rear end...the tag is metal and attached by one of the bolts...it reads dm-j 3 50 788 311

other numbers that are cast into the rear end read

dif
dif 60
7a31
c5aw
4868a
13(or18)

there's one more that is in a circular pattern and i don't know if it's read reading around in a circle or left to right top to bottom...around the bottom left to right is 5.31 at the top left to right is L.8...or if you start at 5.31 and read around the circle counter clockwise it would read 5.31 8.7...hard to tell if it's an L or 7...i'm guessing the gears are 5.31...i'm wondering if it's an L and that's for limited slip...i was looking around some more at sites tonight and noticed this number on a site C5AW-4668-A...could be my 4868a is 4668a...i was reading about tags too and there are different kinds...there is one that sort of looks like mine... i wonder if the 3 50 on my tag is 3.50 gears...thanks

[papabug71]

You only need the #'s on the tag.

dm-j 3 50 788 311

3:50 gears, open diff. No friction modifier needed!

Had it been a "locking" diff. or in real life, a limited slip rear end, it would have read:

dm-j 3L50 788 311

[thebannister8]

thank you all for the information...i appreciate it