SlinkyYJ92

Getting my truck (finally this weekend) and know I have to replace the axle (cheaper than a fix). It's an H9 3:55L. Problem I have run into is searching to see if it is the "Heritage" style or "New" style. I'll have to check but almost 99% positive it an 8.8. It has the 6X135 bolt pattern. It has major noise from the LS so I am just going to swap the entire deal out. I may add the friction mod to it to see but still banking on the swap.
How do I determine what model? I have heard there are differences in the driveshaft length between the two. Also, If I moved up to a 3:73 (I know it a very nominal rpm difference) would it help with swapping TO 32"-33" tires here soon? running right at 31's on the 18" factory wheel.
If there is any useful info I left out (and sure I did) let me know so I can plug it in the equation and hopefully get this figured out. That's why my Jeep YJ runs a 79' F 150, D44/9" 5:38's... simple (but a 4 cyl with 37"AT's & 40" Trepador comps) Thanks in advance!

Z7What

ALL V6s(Non EcoBoost) and 4.6L have 8.8" rearends.

ALL 5.4L have 9.75"

Yes a 3.73 will help with the larger tires. Try a bottle of Friction Modifier first, that's a less than $10 try. Is it humming, if so that's the gears them selfs not the LS and is actually a known issue on the 9.75" haven't heard of the gear issue on the 8.8" which you have.

The DD lengths would be different depending on if it's regular cab, Supercab, or Supercrew and if it's 2WD or 4WD but the axles are all interchangeable. Even if you have a regular cab 4.6L 2WD with a 8.8, a 9.75" from a Supercrew 4WD will bolt right in.

Hope this helps some.

Wayne

Mikegfx4

This is not true. My friend has a 2004 lariat with an 8.8" gear and I have a 2004 fx4 with 9.75". Both are 5.4L engines

Only way to tell for sure is to look at the tags on the axel, there is a lot of information about the axel on there including the stock gear sizes.

Z7What

It is 110% true for the 99-03, I'd bet my house on it!!!

The 04+ I'm not 110% sure but can't see why things would change. I have been on F150 forums for 12-13yrs and this is the first time I have ever heard of what I said above not being true. Did he buy it new? Because honestly my guess is that the rear end was swapped at some point. Or the door was change and has the sticker from the truck it came from. The only true way to tell isn't the sticker, it's to look under the truck and count the cover bolts the 8.8" has 10 bolts, the 9.75 has 12.

I'd love to see a picture of this! But there no way of knowing it the truck was wrecked or axle swapped by a previous owner. Unless he bought it new and has never been in a accident.

Wayne.

SlinkyYJ92

That was my first impression was t drain it, refill and add the friction modifier. It just has the common jerk/pop of an LSD when turning and hard take offs. I had a Detroit in a Cherokee D44 that was horrible about doing so though it turned out to be the shop that messed it up. I was just wondering being pretty high miles near 180K if it was better to swap the whole deal out incase other internal issues had/have/will rear their ugly head. What weight fluid does it take and is it picky on regular or synthetics? Thanks again for the advice!

Mikegfx4

[MENTION=141720]Z7What[/MENTION]
True there is no way of knowing if the axle was swapped or not.

As is there no way of knowing if the axle was swapped on Slinky's truck, which is why he needs to get under the truck and check the tag on the axle.