Okay, I had no idea. So I will unbolt the cover. What kind of sealant do I need to get to put it back together?

Also - on the Valvoline, so I don't need to add the Motorcraft friction modifier, or do I?

 

How long did it take? Will I need PB Blaster for the bolts?

 

Not unless you end up with shudder or chatter. Then you could add some. I doubt you will need it.

 

It's easy. It doesn't take long, but you need to allow some time for the RTV to set up.

Here's some step by steps Welcome to guzzle's Rear Differential Maintenance Web Page
Welcome to guzzle's Front Differential Maintenance Web Page

Unless you got your truck from up North, or have spent a lot of time backed into a lake, you shouldn't need any PB blaster for the bolts. They should break loose with just a ratchet.

 

Did you look at Bill's link at all, back in Post #6.?

He has it VERY well detailed.

Spoon fed, so to speak!

Pop

 

Trey, what fluid did you use? Did you add the Motorcraft friction modifier to it, or did you just go with the modifier present in the fluid?

 

Took me all day but thats because I took my time, waited for things to dry, had lunch, socialized, etc. I needed a pneumatic impact wrench to break the bolts free on the front, I didnt try it with out the air tool on the rear, it was just easier that way.

Any RTV High Temp Silicon sealant will do. Picked mine up at napa for around $5.

The Valvoline will have a friction modifier in it (double check the front of the bottle just it case, it will say "LIMITED SLIP" in a red bar) 75w140 for the rear and 75w90 for the front 3.75 and 3 quarts respectively. I ran with the Valvoline friction modifier and put 100miles on the truck today, no complaints.

 

I had the front done a while back, so I will only do the rear.

 

Permatex has a new RTV sealant specifically labeled for differential covers.............not that you need that one, but I HATE the way Permatex has 50 different products that do almost the same thing. I stand there forever comparing the backs of the packages because the front of ten different products will list the exact same intended usage. So much overlap, they should either tidy up their line or have an application guide on the display.

 

Well, I didn't have the front done on this truck. I was thinking about my last SD. So I will do the front as well. I am going to use Valvoline synthetic 75W-90 in the front.

 

You be surprised how dirty the rear diff oil will be...especially while front diff will still look new. I changed mine the first time at 20K and it was black.

A new diff cover gives you additional oil capacity and a nice drain plug.

 

Thats not good... I changed mine at 145k miles and it was still translucent amber in color.

 

If you don't want any leaking issues pick up a can of the stuff in the link. The gasket maker in the link is an OE replacement sealant. I got seepage using a different type of Permatex and then got the "Right Stuff" and it seals perfectly. You want RTV that gets very firm like the OE sealant. Its not cheap but you get what you pay for.

http://www.permatex.com/products/Aut...sket_Maker.htm

Amsoil sells a Friction Modifier that works with any type of oil I bought a tube and put it in my diff after I experienced some chatter while towing. Costs under $10 for a 4oz tube.

If you have a clutch style LS differential like Fords OE unit you will get dirty oil. I changed my rear diff oil around 32k or so and had quite a bit of friction material floating in the oil. Another reason why I don't like the stock LS unit.

 

I have limited slip too.. still a pretty amber color oil

Also as far as the sealant goes, any RTV High Temp silicone sealant will do. Got mine at NAPA for around $6

 

My old oil was a nice maple syrup color, and my limited slip still works. That's probably not a coincidence.