I've dug up as much info I can, starting with a reciept from previous owner, he returned a 9.75 bearing for a 8.8. So I believed I needed 8.8s I then checked the ID tag after ordering the parts it starts 9.75 differential. So I figured he slapped a wrong bearing in and now the seal is blown. So I don't know if he reused the seal, didn't put it in right or wrong seal and bearing. I can't make out the additional sticker on the passenger side of the axle. Besides 923A.
My ID tag is as follows:

S-923A
3L73 9 75 9C12 -- March 12th of 99

The door sticker for AXLE states B6 --3.73 LS

It is a 99 5.4L.

The only thing I notice is near the wheels the axle gets thinner. (not sure if thats just the 923A)

That leads me to deduce that they will be 8.8s, am I correct before I take it all apart and not have the correct bearings and seals?

Yes, it has the 9.75 differential cover.

I then found out the housing has a stress crack where the seal would be so I need a new axle, was advised to not try and weld it.

Next question, what axles can be compatible with it for interchangeability? I've asked some it can be as long as ratio 3.73 with Locking, others tell me it's the odd year model that is very specific that I have to find a 99 f150 5.4 to match.

I tried this over in the other powertrain section, not getting much bites, didn't see a button for me to move it over here.

 

The only thing I really got out of all of that is you have three sources (door sticker, axle tag, and appearance) telling you that you have a 9.75 rear end and yet you still think you need to order bearings/seals for a 8.8??? Yea, I'm confused. Especially since you found a crack in the housing requiring a new axle. As far as I know, there's no difference between 9.75 axles between years except for disc or drum brakes. Guessing your '99 has drums? I'd find one out of any truck with drums and it should by all accounts bolt right in.

 

That's the only thing that makes me believe it, I read somewhere that they actually had to do that... I do have disk brakes.

My question now solely is based on rear axle replacement, I'm I going to be limited to just the 923A or should I be able to change out as long as the 9.75 and the 3L73 and disc brakes match? I only ask because ordering from the junkyard with inventory they only pulled up this exact match, whereas normally it could pull up other models he said.

 

Why did you start a new thread?

https://www.f150online.com/forums/ot...-question.html

You just lost a lot of continuity.

 

I believe somebody else started a thread on this very subject recently. Search for it because it had some very interesting information on those bastard axles.

 

Don't have to search for it, it's linked in my post. As a matter of fact the thread was started by the same person that started this one.

 

Yes same person. Close her up no reason to keep it open. Either of them.

 

https://www.f150online.com/forums/ot...rear-axle.html

This is the one I was thinking about.

 

Still think it`s a ( replaced,1915 on, super 8.8 ) they have a 12 bolt cover and 34 spline axles, and many internal
8.8 parts, but are beefier. I think I just found out also that the 3.15 housing maybe internally smaller than the other
ratios . THANK ALLOT Ford !

 

As I said in the other old thread you posted in, it's not a Super 8.8. 2015 was the first year of the Super 8.8, and the axle in this discussion is in a 1999. It's a 9.75 with some 8.8 components.

 

Well your correct.... and not...
The discussion is about a 1999 truck .... posted in 10-24-2013
Sooooo your right !

 

2013 to 2021 talk about paying attention...

 

So you must be a little, short ,fat, socialist, POpigS , that likes to criticize everybody
to FEEL dominate.
GROW SOME...boy

 

When I ordered a new axle and wheel bearing for my 2002 F150 5.4L I ordered the wrong axle the first time and had to reorder. My truck has the smaller axle bearings, code 919F if memory serves. Here are some photo of the two axles and bearings.