HunterF150

I have been through it before and must do it again. The rear left is now leaking. I know the rear end is an 8.8, it is a 5 lug, and I have the VIN. I need to figure out the shaft length, spline count, and lug bolt length and diameter in the event I need or decide to buy a complete kit. I have been to fordparts.com and the website does not seem to be as good as it once was. How do I figure that out to narrow it down to the precise axle kit? Is there another website? The parts suppliers like Rock and Summit do not have a function for VIN and somewhat leave one guessing.

Is the kit route generally better than the repair bearing and seal replacement alone?

Since I am in there, draining the rear diff and replacing the fluid and back cover, is it best just to go ahead and replace the bearing and seal on the other side?

BareBonesXL

Pretty pretty pretty sure it's a 31 spline. They didn't go to 34 until well in to the 2000 teens. Not sure that you really need to know length. If you have the year of your truck and model almost any auto parts store will show the correct parts. You don't really need the VIN. The tag on the axle will tell you more.

Can't get the other axle out without removing the C clip so "best" is really a personal choice.

This site is pretty informative - https://www.americantrucks.com/f150-...rain-9703.html

mbb

Unusual to have multiple failures
Did you previously use cheap chinese parts?
Or wheels with more backspacing than stock, spacers, etc?

My stock are fine at 270k......

But yeah, makes no sense to not do both sides....with high quality parts.

HunterF150

I previously replaced the axle shafts, bearings, and seals with the Dorman kits. Those kits are in the $130-140 range, so they are not exactly cheap but I don't how how good or bad they are reputed to be. We visually inspected the parts before installing them and they were round and true and generally appeared good. The truck frame and read end have about 410,000 miles on them. I suppose each axle and bearing lasted about 200K miles.

I went in and found that there is wear on the spider gears and need to replace them. Due to the holiday weekend, the issue with obtaining parts, and help with service, I installed a repaid bearing on the left side to get by for now and will now plan for the rear end service.

HunterF150

Do worn spider gears generally contribute to axle travel or other undesirable events and wearing of bearings and seals?

What is the opinion on rear diff service versus replacement with a rebuild from Rock or elsewhere when only the spider gears are worn? And the pinion seal is leaking a little?

Is is better to drop and replace or replace and repair the individual components?