Diff gears; can't figure out what I have.

[Dsquared]

I have what I think is a 1971, its been in my family since early 70's. I'm trying to figure out what I have regarding gears.

Here are the specs from the tags that I can find.

Trans. RAT AH 2 (three speed on column)
T-Case. Dana model 20 (T -handle)
Front Diff tag. DITA 3002-MB, 603218-3 3.54
9" tag. Missing

Vehicle tag. Tans C. Axle 18

I've checked some of the sites with the t-case and trans specs but I can't seem to get all these numbers to match up right. I think I have 3.50 gears based on the charts. But that front diff tag shows different. Need help!

 

[idahobronc]

Put bronco in neutral. Jack a rear wheel off the ground ,spin you tire one time and count how many times your drive shaft spins.Drive shaft spins will tell you your axle ratio.3 1/2 shaft spins =3.50 gears

 

[cynrays]

If I am right if the back is a 3.50 then the front is probably a 3.51..

 

[Rustytruck]

The front tag says 3.54 and the rear should be 3.5 if you have a matched set.
ford used slightly mismatched gears sets due to dana making 3.54 gears for the front axle and ford making 3.5 for the rear axle. eithor way close enough.
if the gearing has been changed.

Easy way to find out is jack up the axle and hang a string from the drive shaft. Now turn the tire 1 revolution and count the number of wraps the string is on the drive shaft. 3-1/2 wraps of string = 3.5

 

[Skiddy]

yes looks like you have 3.50 gears,(rear) and 3.54 (front) since the gears in the front are not the exact same size is why they are just a little bit different. hmmm hope that made since. Also front dana and rear 9" ford.So they get them as close as possable.
Dang I type way too slow

 

[cynrays]

Sorry i meant 3.54..

 

[Socal Tom]

I have what I think is a 1971, its been in my family since early 70's. I'm trying to figure out what I have regarding gears.

Here are the specs from the tags that I can find.

Trans. RAT AH 2 (three speed on column)
T-Case. Dana model 20 (T -handle)
Front Diff tag. DITA 3002-MB, 603218-3 3.54
9" tag. Missing

Vehicle tag. Tans C. Axle 18

I've checked some of the sites with the t-case and trans specs but I can't seem to get all these numbers to match up right. I think I have 3.50 gears based on the charts. But that front diff tag shows different. Need help!

The front and rear ratios can vary by a couple of percent without a problem. They rarely can be exactally the same since the ring gears are different sizes. 3.54 =3.50 in a D44. Air pressure differences can make a bigger difference to the final drive ratio than 0.04 out of 3.50
Tom

 

[broncnaz]

axle code 18 is for 3.50 gears 2900 lb axle Small bearing I believe as 3300 lb was the big bearing axle. yes your front is 3.54 because dana doesnt make a 3.50 but I've also heard it helps keep the drivetrain from binding up.