Can anybody help me Identify this number code I pulled off my Pumpkin.
and will a 9" 2.47 ring and pinion set work with it.

Here is what is on the tag.

??DM-CK OK16
25 9 S317B

Here is what I do know,

1981 F150 Ranger 300 Straight Six
3 speed automatic, no limited slip rear axle
Runs high RPM's @ 65 going down the highway

 

From the tag, it looks like a 3.25 ratio, which is a good in-the-middle ratio, maybe even a tad high for a truck. You're going to hate it if you switch to 2.47's...

If you're really set on doing this, just swap third members out. That way you don't have to re-setup the gears.

 

Usually that bottom left number is the ratio. On the tags it looks more like 2 59. All the ford rear ends I've had have been this way. What's the axle code on the door jamb sticker?

I bet the other (first number) is under or near the bolt holding the tag on. I can barely see the 3 on mine. I know what you're talking about, my 351W is reving pretty high out on the highway. I love this C6 but an AOD would be very nice to have.

Bad thing about just slappin some high gears in it is it affects the other 2 gears you have to use to get going.

These trucks were built way before these higher speed limits. They don't seem to like it much. Mine loves to run at 55 mph, just sounds happy, which was the speed limit at the time and it's even circled on the speedo. Dang, I'm old enough to remember the national 55 mph speed limit

 

Get the axle code off the door sticker and post it here. Someone will decode it for you.

 

Is there another place besides the door and rear axel tag that would have the axle code. One you cabt read and the other one just isnt there.

 

So there's no sticker on the drivers side door jamb? You can remove the tag off the axle, clean it up and you should be able to read it. Don't know of any place to get the ratio.

You probably just can't see the 3 near the bolt very well. Like andy said, it's probably 3.25 ratio.

You can also try rotating a tire with it jacked up. Just mark the tire and driveshaft. Turn the tire 10 rotations, count how many times the driveshaft goes around. Then just devide the driveshaft number by 10.

Example...turn tire 10 times, driveshaft turned 32.5 times...32.5 divided by 10 is 3.25 gear ratio.

 

tgore3, Doesn't your method only work for limited slip axles with both tires off the ground? I think for regular axles with one tire off the ground the driveshaft will rotate half that many turns due to the action of the differential i.e., 16.25 turns (so divide by 5).
Click this link for an explanation: http://www.efunda.com/designstandard..._auto_diff.cfm

 

Oh yeah, I think you're right about that. I'd only done it on Mustangs with trac-locks.

So with one tires off the ground you'd divide shaft rotation by half of your tire rotation.

 

Well it turnes out I was Looking in the wrong spot, my axel code is a 15

 

Here's a chart that's here on FTE https://www.ford-trucks.com/article/...de_Chart_.html

My code is 16...I don't see yours or mine on there

 

I found another chart that seems to have what we're lookin for. It matches up with the axle I have. So, you've got an open 9" with 3.25 gears.

Ford Rear axle codes used from 1981-1986
13- Ford 9" 2.75 ratio 1981-83
13- Ford 8.8 4.11 ratio 1985-86
H3- Ford 9" ls 2.75 ratio 1981-82
H3- Ford 8.8 axle 4.11 ratio with limited slip 1985-86 (3800 pound)
14- Ford 9" 3.00 1981-1986
H4- Ford 9" 3.00 Limited slip diff 1981-86
15- Ford 9" 3.25 1981-82 and 2.73 in 1983
H5-Ford 9" 3.25 limited slip 1981-82 and 2.73 in 1983
16- Ford 9" axle 3.50 ratio (3750 pound)verified
H6- Ford 9" axle 3.50 ratio with limited slip (3750 pound)verified
18- Ford axle 8.8 3.08 ratio (3800 pound) 1983-86verified
H8- Ford axle 8.8 3.08 ratio limited slip (3800 pound) 1983-86verified
19- Ford axle 8.8 3.55 ratio (3800 pound) 1983-86verified
H9- Ford axle 8.8 3.55 ratio with limited slip (3800 pound) 1983-86verified
23- Dana 60-3 axle 3.54 ratioverified
24- Dana 60-3 axle 3.73 ratio verified
29- Ford Semi Float Sterling 10.25, 3.55 ratio
B9- Ford semi Float Sterling 10.25, 3.55 ratio limited slip diff
B5-Ford semi Float Sterling 10.25, 4.10 ratio limited slip diff
39- Ford full float Sterling 10.25 3.55 (single rear wheel)
C9- Ford full float Sterling 10.25 3.55 (single rear wheel) with limited slip diff
35- Ford full float Sterling 10.25 4.10 (single rear wheel)
C5- Ford full float Sterling 10.25 4.10 (single rear wheel) with limed slip diff
33- Dana 61-1 3.54 ratioverified
C2- Dana 61-1 3.54 ratio with limited slip diffverified
52- Dana 70-1 HD 4.10 ratio (8700 rating)verified
53- Dana 70-1 HD 3.54 ratio from 1983-86 (4.56 in 1982) (7400 rating)verified
E2- Dana 70-1 Hd 4.10 ratio with limited slip diffverified
49- Ford Sterling 10.25 dual rear wheel 3.55 ratio (7400 rating)verified
D5- Ford Sterling 10.25 dual rear wheel 4.10 with limited slip diff (7400 rating)
69- Ford Ford Sterling 10.25 dual rear wheel 3.55 ratio (8250 rating)
F5- Ford Ford Sterling 10.25 dual rear wheel 4.10 ratio limited slip (8250 rating)

 

Well that narrows it down. But unless the tag's wrong, it's a 3.25 ratio. Like others have said, the first digit is often covered by the bolt. If you remove the bolt, you will be able to see the 3.

People miss the first number ALL THE TIME. I've gotten to the point that I don't even comment on it anymore, I just tell them what the ratio is.

 

Do you have a tach in your truck or are you just going by the sound of the motor out on the highway? I've had 2 of those 300 I6's and they sound like they're coming unglued even at moderate rpm.

 

Na there is no tach but I am trying to figure out what that RPM's going down the Highway.I have tryed to do those calulation but always get stuck because I Dont know the the actuall transmission gearing is. Like I know the rear end now which is a 3.25 but what would third gear be 2nd and 1st.

here is what is on my tag

http://s105.photobucket.com/albums/m230/bryanswens/

 

Yeah, you'd have to know your tranny final gear ratio, rear end ratio, and tire diameter.

We know you have 3.25 gears, C4/C6 tranny has 1.00 ratio 3rd gear, all we need is your tire diameter.

You're probably turning 2600-2700 rpm @ 65 mph