I have a 2000 F150 5.4 4x4 and the driver side rear wheel bearing just went out and it damaged the axle. I take the tag off the hogs head and one of the old bearings to the parts store with me to see what I need. The tag says the axle and bearings are 9.75 but those bearings are way too big. I got the 8.8s and they fit perfect and match the ones that came out of the axle housing. Then we get to ordering the axle. I get it today and it is exactly like the old one except it has 31 splines and the old one has 34. Nothing in the computer at the parts store has an 8.8 axle with 34 splines, they all have 31. Only the 9.75s have 34 splines in their computer. So they aren't sure what I need to order, they ordered another one today to match the tag but its a 9.75........Anyone else have this issue before?

 

You have one of the bastard axles - it's a 9.75 but with some 8.8 parts.

 

So where do I find the correct axle to fit it????

 

What's your axle tag data? Everything, please. If the parts store matched up tag numbers you should get the right one this time.

 

S 919 D<br/>L55 9 75 9 LC 8<br/>

 

I have one of them in my truck, I found out when I needed to do the axle seals. I was under the impression that only the axle tubes are from the 8.8 so you would use 8.8 bearings and axle seals but the axles themselves are still 9.75. Is that not correct?

I thought I compared the 9.75 and 8.8 axle seals when I went back to the auto parts store and the center hole size was the same. I could be mistaken it was a few years ago now.

 

I see that the axle diameters are indeed different but I did find that Rock Auto has Dorman axles that are 8.8 diameter and 34 3/8" long, 34 spline to fit with 9.75 ring gear. Axle code 919D.

Part #630241 for left side

Part #630219 for right side

They may have others but that will get you started.

 

Ford part numbers:

Left: F75Z4234MB
Right: F75Z4234MA

The 919D is the key.