awhile back someone hinted at me that i could find a used set of rear end gears for my 250. I need to lower the ratio (raise it? i dont know much about that stuff) so that i cant drive above 60 on the highway and make slightly better gas mileage. Anyone know where the best place to look for those gears would be?

 

For better gas mileage, you need lower numbers. Going from 3.75 to 3.25 would slow the engine revs at 60.

Problem is the Dana 60 that the 250s have, is not like the 9" that the F100s have. You can't simply swap them out. It is a lot more precise and complicated.

May I suggest to you, to do more research first on the cost of the swap.



John

 

where would i go for this info? what specifically am i looking for? would it be feasible to switch the rear end out completely for a 9 inch? or would that just be a huge pain in the ***?

 

First find out what ratio you currently have. I think the most common ratios are 3.73 and 4.10. My 67 has a 4.10. Do a search on the web and check out the different sites for Dana parts. You could also find a better ratio from a later truck and swap the complete rear end. I understand that the 250 did not go to the wider rear end until sometime between 76 and 79. Even the wider rear from a newr truck will work with some modification (spring perches and shock mounts) search this website for more info on this. I have never changed gears in a Dana so I do not know what all is involved

 

I thought Bill da Dummy would have stopped in to help.

The factory ratio should be on the door plate at axle code.




John

 

It is relatively a lot of work to swap gears properly in a Dana 60 - I have done it several times. Differential bearing preload, pinion depth, backlash all need to be correct to survive and run quietly. In my opinion, anyone who does not completely understand those terms should not be allowed to touch your truck's axle... I think your best bet money-wise would be to just swap entire axle assemblies.

Look for a 67-72 F250 with a "37" axle code, it will be a 3.54 ratio which is approx 5% less RPM's than the "38" axle code 3.73 ratio, and approx 14% less RPM's than a "24" axle code 4.10 ratio. A "C7" axle code is even better, it is the same ratio and 5300# weight rating as a "37" but with a locking differential. A lower numerical ratio reduces RPM's. Less RPM's at cruising speed helps gas mileage and reduces engine wear but reduces acceleration and towing power. 3.54 is the numerically lowest gear ratio I have ever seen in a 67-72 F250. I have seen 3.07-geared Dana 61's used in F250 trucks, but those were 1977-79 trucks with 400's and automatics. Newer axles will be too wide to bolt into your '69 F250.

Where are you located? Perhaps another FTE member has an axle and is near you.

I am near Milwaukee, Wi and have axles and parts.

 

Im in Texas. ive been told (by the people at JEGS) that i could just swap out the whole damned differential, and decide what ratio i want when i order it. I figure for 500 bones it might be worth it. coupled with the 5spd swap im planning, i could conceivably hit a happy medium of (somewhat) decent fuel mileage and towing capacity. i hope.

 

The problem is John, there are 500,000 members on FTE, and only one of me (you're prolly thankful of that! ).

Since I can look up parts for a 1928 or a 2002 and every year in between, I'm kinda busy.

The AXLE code is listed on the Warranty Plate, which is located (thru 1980) on the left door face below the latch.

On the rear axle itself, the Ford ID tag is under one of the bolts that holds the inspection cover on. But today...most of these tags are missing.

The Dana ID tag was bolted to the housing to the left of the inspection cover (to the right on 4WD's).

The tag is 2" x 1/2" and has a 7 or 8 digit code on it. Like these examples: 603010-1 or 602010-11.

The lowest numerically ratio available in Dana 60's thru 1979 was 3.54-1.

Beginning in 1980, 3.07-1 and 3.23-1 gears were also available.

Finding any of these three ratios will not be easy, especially the 3.54-1 ratio.

The width of the Dana 60 rear axle changed in 1973 for F250 2WD's, and...

After serial number Y20,001 in 1977 for F250 4WD's (Y20,001 = last High Boy).

EDIT: AXLE codes 37 & C7 were used for the 3.54-1 ratio from 1967 thru 1982 only.

1983/86: 3.54-1 AXLE codes are: C3 & 33.

If the AXLE code begins with a letter: Limited Slip.

If the AXLE code begins with a number: No Limited Slip.

 

i just picked up a 72 f250 rear to swap into another truck. tag says 3.73, should the pinion gear be stamped the same? or do the numbers on the pinion gear count. just trying to figure out if i really have a 3.73 or not.

 

I think it's a huge misconception that higher gears will get a lot better mileage. The mileage increase you actually get for all the work of changing gears will be disappointing. If you have a 3.73 for instance and go to the 3.54 (lowest ratio for a D60) the difference won't even be measurable. Cheaper and easier to just get back tires a couple inches taller. Or better yet, just drive 5-8 mph slower and get a 15% increase in fuel mileage and that doesn't cost anything.

 

C7TZ-4209-E .. 1967/72 F250 Dana 60 / 3.73-1 / 41 ring gear teeth / 11 pinon gear teeth.

3.54-1 introduced in 1966. Many people want one, few find them.

3.07-1 & 3.23-1 intro'd in 1980. If you think 3.54's are hard to find, y'all may have better luck finding Jimmy Hoffa, than one a these puppies.

 

I just bought a Dana 60 rear end today for my 1950 Ford F2, it came off a 1962 Ford F250, the axle code on the tag was a number 24, I was expecting it to have the 4.10 gear ratio but the actual rear end had the little plate marked with a 3.73, the truck was a unibody, I don't know if that would make a difference...I actually wanted the 3.73 and was settling for the 4.10 so I guess I just got lucky...I know it is an old thread but it seemed interesting to me that the code didn't match...perhaps because it is a 1962 instead of a 67-72??

Thanks,

Luis

 

I have a somewhat related issue... I have a '69 F-250 with the Dana 60, open with 16 spline axle shafts. I have available to me a later Dana 60, posi with 30 spline spider gears. Anybody know what axle shafts might work? or do I need to find 16 spline spider gears for the posi (assuming the spiders for the open diff are not the same?). Thanks to whomever can help shed some light on this for me.