The topic of 9" vs 8.8" has been a huge debate in the past. The end result of all the discussion was that the 9" and 8.8" were for all intents and purposes considered equal in strength...they're different axles though.

It's a matter of taste but just understand the facts before you do something for the wrong reasons.

 

Well ... the reason some of us like the 9 is because several center chunks can be setup with various ring and pinions ratios and installed depending upon how we need to use the vehicle. And if I have to change it anyway .... I would rather put one in that doesn't have the history of pinion nuts getting loose.

 

I had quite a few 8.8s in F150s and all I can say is they are not for pulling or carrying any load. If you just use it as a driver, you will be fine. As for 9" and 8.8s being of equal strength. Yeah Right!!!!!!!! The 8.8 has no pinion support bearing and when they get any serious load against them, the pinion teeth just break off as they spread apart! your ring/pinion contact area decreases as the end of the pinion pushes away from the ring. This CAN"T happen with a 9".
My application was a 1988 Ford Bronco that I swapped in a 6.9 diesel and C6(not really a torque monster) The original 8.8 3.55 ratio seemed ok with the original 5.8 C6, but came loose after my first tow, a car on a tow dolly. It tore teeth of pinion and ring gears, next one I rebuilt and used low mile diff with new yoke/bearings,seals . I caught it before it exploded, only around 3000miles on it, not all towing either.
So I put in a used, 1986 9" 3.50 with limited slip, new seals and fluids(bolt in!) I had it for 1.5 yrs and close to 15000 miles, 2 trips to Arizona, pulling old trucks home to Ontario. I sold it in 2001 and the owner pulls his mobile saw mill with it and has replaced headgaskets on the motor but is still running on same 9" !!!!!!!!!!
The only reason the 9" isn't as popular as a 8.8 is that the 9" has not been made for almost 20 years and the Racer have used them up!
8.8s belong in Rangers/Mustangs/Aerostars. Just my observations.

 

Hey all! One of my friends drove my truck and said he never heard such a noise coming from the rear axle. We opened it up and it looked OK so we refilled the fluids (yes, added the anti-slip additive) and buttoned it back up. My friend and a buddy of his, who is a mechanic, think its the bearings only. I was considering a 4.10 upgrade but we feel with the torque monster that the 392 is it would really be a waste of ~$1000.
I do pull a 5th wheel trailer and they believe I need to get this ck'd out ASAP before our next trip in a few weeks. I realize this is difficult to troubleshoot but what do you all think?
Currently looking for a 250 to get the better axle with 8 lug wheels and bigger brakes. I've got so much $ in my rig I'm better off doing that than replacing it. Plus I understand its not difficult or necessarily that expensive.