white89gt

I was going to ask this as well until he said a shop actually repaired it with JB Weld at some point.

RVT1KR

WTF!? I missed that

BigEd54

To clarify one bit of misinformation, the replacement does not need to be the same ratio or diff type. Swapping the rear end is the easiest way to change axle ratio. I replaced my 3.08 open diff with a 3.55 LS.

You do have to match the mounting hardware and brake type. The best way to ensure that is to have the salvage yard guys look it up for you on their compatibility charts. There are numerous axle codes from various vehicles that will work on your truck.

Axle tubes are 1/4" steel. That would have to be some pretty bad corrosion to penetrate. At that point I would suspect the tube was not structurally sound.

In theory, you can absolutely buy a new rear housing and install all your old parts in it. However, you have to know how to set up an axle, which is not a beginner job. Also, the internal parts are probably worn out and need to be replaced. So, it's more cost effective to just swap in a complete axle assembly. If you do that, I recommend you consider rebuilding the new one before you swap it in. Much easier on a bench or stand, and only about $100 extra in parts.

white89gt

And to clarify your one bit of misinformation, his speedometer would be off if he changed gear ratios. I do agree, he could put the larger diff in, BUT, he will also need the proper u-joint to make that work. This adds cost to convert and make everything right.


And again, more misinformation. He can use the differential out of an F150 ONLY. There are no other Ford trucks that came with a 5 X 135 mm bolt pattern, except the Expedition - which uses a coil spring. So again, you're back into adding costs to convert.

akdoggie

My turn for my 02 cents.

2003 is a 9.75 rear axle, unless it is a 2wd truck with a v6. It could have the 8.8. Others all have the 9.75. Your year only has a limited amount of application options. Only F150, from 11.29/99 (early 2000 model) thru the 04H series. Nothing else fits our GEN 10's. You need this application because of the swap from 12mm to 14mm studs and heavier axles over the 97-99 units. A complete swap is a simple 2 hour job on the ground. You must make sure the right side ebrake cable is the correct length to have them operational. All 139wb use the same length cables. 120wb only their cable and 157wb a different cable too. Only on the right side.

To the OP. If you have the V6 engine, which you do, you could have either an 8.8 or 9.75. Most likely the 8.8. You need to count the bolts on the cover to verify what you have. 8" Ring Gear, 3.55 Ratio H9 Here is what is available thru the Hollander network. https://www.hollanderparts.com/used-...ar,-3.55-ratio

white89gt

Hmmmm.... when I looked it up, it said it was an 8.8, 3.55 LSD in this chart. I did not see the year crap on the end though. Looked it up on another chart, and all it says is 3.55 LSD, nothing about WHICH axle it is.

River1

I can't say I'm up on all that's been written about this axle question but axles are very nuanced. I've seen a lot websites say so and so part won't fit because axle ID's don't match but the parts actually will work fine. I've picked up 8.8" gears from Watson Racing that were pull offs from new Mustangs that work fine on the F150 but if you looked them up on a site like Rock Auto it will say "this part will not fit your application," which isn't true. I've also picked up axles that were exactly the same except for pinion angle locating pins. An easy fix but from what's written you'd think there's no way to make the part work without major fabrication. Not true again. Then again there are axle mismatches that would be a nightmare to try and use.

There's a book by Joseph Palazzolo called Ford Differentials, How to Rebuild the 8.8 and 9 Inch that is very helpful with a lot of the picky nuances identified by axle nomenclature. Although the title says 8.8 and 9", there is a lot about the 8" and 9.5" along with front axle information and coiled spring pocket kit installations.

D56auction

You guys are all so helpful. I really appreciate all the input. So the left tag says ?L55 88 3H1 I think this is an 8.8 inch ring gear 3.55 ratio, right? Now the question is can I use anything else in case I find something cheaper, closer, or in better condition? I understand the speedo issue which is not a big deal for me but unsure about other "issues." Here's a picture of the problem area so if any of you think I'm barking up the wrong tree with the rear end replacement speak now or ....'s

Sorry the picture's so giant...haven't figured out how to make it smaller. Hey, give me a break, I'm old. I keep reaching for the choke switch out of habit and try to dim the lights but I can't find the damn button on the floor.

River1

Have you tried just getting that welded? You have to be careful though. There are a lot of welders that will say they can weld the casting but maybe 1 in 10 are what I would consider qualified for that job but there are welders that specialize in casting. Locally there is a weld shop that specializes in welding fixtures used in dipping processes in caustic liquid tanks. They don't make new fixtures, they're just welded and re-machined. They've got a good reputation locally for shorting axles for dragsters and they have the equipment for doing this kind of work.

white89gt

One thing that would concern me is this area. This looks like it is pretty thin right here. I would bet that a little tapping with a hammer would open that right up.