Under my truck there is diff oil slung all the over the underside. There is a small bead of oil that will run out of the pinion right after i park it. Now it doesn't send out a spray or anything that bad, but it's bad enough that after a drive to work it has covered the underside half way up the drive shaft.

Now I just thought, hey i'll replace the pinion seal and life will be good. But then i was told by that it could be the universal joint going out... if it was the universal wouldn't i notice shaking or vibrating at high speeds?

 

crawl under there and try to move your drive shaft in all derections to see if you have any play in the u joint, good luck

 

Yes, check the U-joints, but they only contain a small amount of grease. They don't "sling out differential oil", "run a small bead of oil out the pinion" or "include enough lube to cover the underside halfway up". By the time the factory U-joints are shot, they're usually almost dry. Leaking pinion seals are a very common problem. I would do a search because there is already substantial information in the archives. You will find several opinions on the replacement procedure. Typically, you'll see a gear oil trail leaking down the front of your rear end below the pinion seal.

 

Yeah, it's all over underneath the pinion, i'm guessing as it comes out some of it is being slung on the underbelly. Also a small pool forms after driving it then parking it. By small i mean about the size of two quarters.

I want to get the seal this evening and begin tear down tomorrow morning. The problem i'm having is there are different size seals listed at the different part stores websites. I have a 5.4L offroad lariat, there's an 8.8, 9.75, 10.75... i really don't want to trust the kid behind the counter to get it right.

 

you should have the 9.75, you can look back at the axle is it kinda shaped like a stop sign? i am 99% sure that you have a 9.75 with a 5.4 only the 4.6 has the 8.8 and the 7700 F-150s have the 10.75, good luck

 

7700? Which one is the Heavy Duty? I assumed i would have that because i have the towing package.

 

I have tried using my VIN to find out information on my truck but i can't find a good website... any one know of one?

-realized my vin won't tell me, i'll have to look when i get home. I thought i would be able to find exactly what was on my vehicle.

 

the 7700 is the light duty F-250 looks like a f_150 body but it has tougher suspension and better payload capacity, you would know if you had one, you most likely have the 9.75 axle,

 

How would i know if i have one?

besides looking underneath. I know i have the heavier duty transmission that is an option on the F250.

 

Here you go.

http://www.autozone.com/servlet/UiBr...%7ENONE%7C%7EB

 

I just had my ring and pinion replaced. After driving the truck for 2 days I noticed a vibration and a leak around my pinion seal. I took it back today and they found out that the u-joinrts are bad and they need to replace the drive shaft. The parts won't be in unbtil next week so they have torn down waiting. I hate not having my truck.

 

If you have the 5.4 look to see how many lug nuts you have. If you have 5 then you have the 9.75. If you have 7 then you have the bigger one.

 

I'm fairly sure ya'll are right, the code on the tag is
s 919 0
155 9 75
9L22

I'm not sure what all that means but i recognize the 9.75.

thanks for all the help guys, i'm hoping to do this today so i can start driving my truck again, the universal joint doesn't budget (THANK GOD!) and it's a sad sight seeing my truck just collecting leaves.

 

Thanks to all who gave input. I pulled out the drive shaft and replaced the pinion... while i had it torn down i decided to replace the universal... my first. Luckily my dad used to be a mechanic and walked me through it. It really wasn't that hard... but i can see where the pain would be. Getting the old universal out. Luckily we have a packed garage with a hydrolic press and it was a peice of cake. I bought the heavy duty universal.

After getting the universal out we found that two of the ends were developing several flat spots. The pins were also bone dry and looked a little funny. not sure if this is normal for 150k. After replacing both i have had one leak, even after using the wrong RTV on the back plate... oops. I used black but not the heavy duty made for high temps.

I wanted to thank everyone who responded... this website has been great for me since i bought my truck and i've recommended it to my step dad and brother who both just bought 2006 F150's... i'm jealous... thanks again!