Hello everyone!

As I'm FINALLY getting back to work on my old 1985 F250, Sanford, my attention shifts to my rear Axle assembly. The truck is an axle code 73, which, I have been told, means its the Dana axle, 3.54 gear ratio, open rear. I have not pulled the rear cover yet to verify the gear ratio ( they still stamped them in the ring gear, right?) but the axle has all the seals leaking, needs brake work, the list goes on.

I recently parted out a 1991 F250 that had an axle code 39, which is the Ford 10.25, 3.55, open. I'm considering swapping this axle in. My reasoning for this is that I have this same axle in several other trucks, so therefore, my stock of "emergency" parts would be smaller, and also, I feel a bit more confident working on that axle, as I've been through several others. also, if i recall, isn't the Dana axle where you need to pull the axle shaft and bearings to get the drum off? i know the 10.25 drum just slides off.

Anyway, is there any reason I couldn't do this swap? Any reason i shouldn't?

 

I think you are describing the difference between a full floating axle and a semi floating axle. Both the Dana and the Sterling were available in both configurations. The full floaters were for heavier vehicles, but the F250 was available in different capacities. Check your door tag.

Otherwise, no reason why you could not swap one for the other.

 

Both the 91 axle, and the axle that is currently in Sanford are full floating axles. I rid my collection of semi floating 3/4 ton axles many moons ago.

 

On some of the old Dana's, you did have to pull the axle to get the drum off, and they were full floater axles also. There is a chance you might need a different length driveshaft if the nose of the rearend is a different length.

The Ford Sterlings of the early years like that are prone to pinion spline wear, which loosens the large pinion nut, so check and tighten the nut if it needs it.

 

Are you sure the AXLE code printed on the Certification Label (glued to the left door face) is 73?

73 = Dana 70U rear axle; 3.54-1; no Limited Slip; 6,300 lbs. axle capacity.

 

I had a Dana in my '84 at one time and yes, you had to pull the axles and remove the drum and hub assembly in one piece. The Sterlings use a separate hub so the drums slide off without pulling the axles. The '91 axle will have a rear ABS sensor in the top of the housing and an exciter ring next to the ring gear inside but that won't make any difference in your truck. Its a bolt in swap but you may need to shorten the driveshaft slightly, or use the shaft from the donor truck assuming they are the same wheelbase. As I recall the yoke is farther forward on the Sterling.

 

We went through this already in the "Adventures of Sanford" thread. the code is 73, but ford used the code 73 as a different code in 85 as it did in other years. And I'm going to pull the cover to absolutely verify that it is a 3.54 ratio.

 

Donor truck was a 2wd, so the driveshaft wont even come close to working. I kept the ABS sensor intact when i plucked the axle from the donor truck, it's just along for the ride, filling the hole now. I'll give it all a measurement once i get it swapped in, if i need a driveshaft, i need a driveshaft.

The ability to easily check my rear brakes is a good thing in my eyes. I like the idea of checking stuff out periodically, to make sure all is well.

Now, will the 85 parking brake cables work, or do i need to source a set from a 91 F250...

 

 

Here is the Axle sheet i got from Gary's site. it says that the "73" code was a 3.54 until the 88 model year, which is when they used the "73" code for the 5.13, 11k axle, as you stated.

Axle Ratios - ???Gary's Garagemahal

As with everything, different charts can be skewed. My decade or so of working behind a parts counter knows that all too well. And I know you, NumberDummy, spent MUCH more time staring at these charts than i have.

The only logical thing to do is to pull the rear cover on the current diff i n Sanford, and verify what gear ratio it is. I will definitely keep you updated on this as well.

 

2WD has nothing to do with it. Difference will be in the Dana to Sterling pinion measurement.

Pretty sure you will need parking brake cables from a Sterling as well.

 

the 2wd driveshaft is noticeably longer, due to the lack of a transfer case, so the donor driveshaft will do nothing to help me there. I'll just measure it all up when i swap the axle in.

 

The Dana rear may use the 1330F ujoint. I don't recall what year Ford switched to 1350 ujoint . It was early 90's ,I think.
My '89 10.25FF has a 1330F ujoint.