Rear differential maintenance

I'm planning on opening up the rear differential and giving a thorough check this weekend. I have a few questions before I begin though.

1. for the '94 S15 4.3L (W) the parts store has two different sized gaskets. Can anyone tell me the correct size for this vehicle? Otherwise I'll just get both and use the one that fits and return the other.
2. How much do I need to drive the truck to warm up the diff fluid?
3. What is the "best" type of fluid to replace it with? Synthetic?
4. What volume of differential fluid is needed for a complete refill?

Any other tips for this job?

I'm planning on opening up the rear differential and giving a thorough check this weekend. I have a few questions before I begin though.

1. for the '94 S15 4.3L (W) the parts store has two different sized gaskets. Can anyone tell me the correct size for this vehicle? Otherwise I'll just get both and use the one that fits and return the other.
2. How much do I need to drive the truck to warm up the diff fluid?
3. What is the "best" type of fluid to replace it with? Synthetic?
4. What volume of differential fluid is needed for a complete refill?

Any other tips for this job?

7-5/8th is your gasket size.

You don't need to warm up the diff fluid

Synthetic or Durablend, or regular... (Personally I use durablend) They'll all be fine. Also good for high miledge diff... You will need 80/90
2 quarts should do ya...

Now, when you have the cover off, put a pan underneath (obviously) and then spray a couple of cans of Brake Klean inside the diff to clean it out. Let it evaporate. Put the cover back on...:)

Also remeber NOT to use any Lucas product in your rear end.

It is proven to cause foaming which is horrible for lubrication.

Also, some synthetic rear diff oil is 75w90 and is perfectly fine.

Thanks for the tips guys. I'll let you know how it turns out. :cwm27: