Need to service rear diff. how to do it?

I bought what was the recomended fluid for the diff. at the dealership today. I took a quick peak under there to see what I might get into. I'm not totally sure what I need to do. It looks like there 2 plugs facing the driver's side. One being the filler and other being the drain. Does this sound right? Anything special I should know? Thanks.

No special procedure, just drain and refill. The two plugs you saw are the correct ones.

I think its a bit more then just drain and re-fill. I swiped this from elsewhere and have included both RDM and transfer case fluid change (this is Pontiac version, I think it should be the same for vous):

Here are the procedures to change the Fluids in the Rear Drive Module (RDM-rear axle) and the Transfer Case (front).
RDM:
1. Raise the vehicle. (You might be able to access the plugs without this step. Just raising one end of the vehicle might not allow the fluid to drain properly and I doubt many people have access to a hoist)
2. Clean any dirt from around the drain plug.
3. Position an oil drain pan under the plug.
4. Remove the plug and gasket (washer?) from the differential and drain the oil. (It appears that they use a recessed/Allen headed plug, definately metric. Make sure that the head of the plug is thoroughly cleaned of dirt and the Allen head socket is firmly seated in the recess of the plug, you do not want to strip the inside of the plug as the repair could be pretty expensive).
5. Once the fluid has drained out, install the drain plug and gasket. Tighten the plug to 32 Nm/23 lb ft. Torque on this plug is important. Due to the material used for the case, you don't want to overtighten it (it will stip the threads) and you don't want it too loose or the plug will vibrate out.
6. Clean the dirt away from the fill plug. Remove the fill plug.
7. Fill it with the proper Versatrak Synthetic Fluid (GM U.S. Part # 123878514, Canada Part # 88901045), adding 2.1 qts./1.9L of fluid. It should be filled to the bottom of the plug hole or no lower than 6 mm/0.25 in of the hole.
8. Install the fill plug using the same note from the drain plug above (same type of fastener). Tighten the fill plug to 32 Nm/23 lb ft.
9. Lower the vehicle (If it was raised)
10. Drive the vehicle in several tight circles going left and right. This distributes the fluid around the clutch packs and gerotor pumps. This is a very important step.
11. Raise the vehicle again (if done previously).
12. Remove the fill plug and check the fluid level. Add fluid as required so that it is no more than 6mm/0.25 in from the opening.
13. Install the fill plug and tighten it to 32 Nm/23 lb ft.
14. Lower the vehicle (If it was raised).

Transfer Case Fluid Replacement. Two fluids are used in the transfer case. The main body of the transfer case that contains the hypoid gears shares its fluid with the transaxle. So to exchange that fluid you will have to drain the transaxle fluid and replace the transaxle filter. The rear extension housing of the transfer case, containing the bevel gears is filled with the same Versatrak fluid used in the rear axle. Here is how to drain and fill the extension housing:
1. Raise the vehicle (again you might be able to access this without raising the vehicle, but it must be safely raised, supported and kept level to allow proper drainage.)
2. Clean around the fill plug and the drain plug.
3. Remove the fill plug and gasket.
4. Place an oil pan under the drain plug.
5. Remove the drain plug and gasket. Allow the fluid to drain.
6. Install the drain plug and gasket. Tighten the drain plug to 32 Nm/23 lb ft.
7. Fill the extension housing with the proper Versatrak Synthetic Fluid (GM U.S. Part # 123878514, Canada Part # 88901045), adding 290 ml/0.6 pints of fluid.
8. Fill the transfer case up to the bottom of the oil fill plug hole. Note: this one must be full.
9. Install the oil fill plug and gasket. Torque the fill plug to 28 Nm/21 lb ft.
10. Lower the vehicle, if raised.

Hey thanks!

I think its a bit more then just drain and re-fill. I swiped this from elsewhere and have included both RDM and transfer case fluid change (this is Pontiac version, I think it should be the same for vous):

Here are the procedures to change the Fluids in the Rear Drive Module (RDM-rear axle) and the Transfer Case (front).
RDM:
1. Raise the vehicle. (You might be able to access the plugs without this step. Just raising one end of the vehicle might not allow the fluid to drain properly and I doubt many people have access to a hoist)
2. Clean any dirt from around the drain plug.
3. Position an oil drain pan under the plug.
4. Remove the plug and gasket (washer?) from the differential and drain the oil. (It appears that they use a recessed/Allen headed plug, definately metric. Make sure that the head of the plug is thoroughly cleaned of dirt and the Allen head socket is firmly seated in the recess of the plug, you do not want to strip the inside of the plug as the repair could be pretty expensive).
5. Once the fluid has drained out, install the drain plug and gasket. Tighten the plug to 32 Nm/23 lb ft. Torque on this plug is important. Due to the material used for the case, you don't want to overtighten it (it will stip the threads) and you don't want it too loose or the plug will vibrate out.
6. Clean the dirt away from the fill plug. Remove the fill plug.
7. Fill it with the proper Versatrak Synthetic Fluid (GM U.S. Part # 123878514, Canada Part # 88901045), adding 2.1 qts./1.9L of fluid. It should be filled to the bottom of the plug hole or no lower than 6 mm/0.25 in of the hole.
8. Install the fill plug using the same note from the drain plug above (same type of fastener). Tighten the fill plug to 32 Nm/23 lb ft.
9. Lower the vehicle (If it was raised)
10. Drive the vehicle in several tight circles going left and right. This distributes the fluid around the clutch packs and gerotor pumps. This is a very important step.
11. Raise the vehicle again (if done previously).
12. Remove the fill plug and check the fluid level. Add fluid as required so that it is no more than 6mm/0.25 in from the opening.
13. Install the fill plug and tighten it to 32 Nm/23 lb ft.
14. Lower the vehicle (If it was raised).

Transfer Case Fluid Replacement. Two fluids are used in the transfer case. The main body of the transfer case that contains the hypoid gears shares its fluid with the transaxle. So to exchange that fluid you will have to drain the transaxle fluid and replace the transaxle filter. The rear extension housing of the transfer case, containing the bevel gears is filled with the same Versatrak fluid used in the rear axle. Here is how to drain and fill the extension housing:
1. Raise the vehicle (again you might be able to access this without raising the vehicle, but it must be safely raised, supported and kept level to allow proper drainage.)
2. Clean around the fill plug and the drain plug.
3. Remove the fill plug and gasket.
4. Place an oil pan under the drain plug.
5. Remove the drain plug and gasket. Allow the fluid to drain.
6. Install the drain plug and gasket. Tighten the drain plug to 32 Nm/23 lb ft.
7. Fill the extension housing with the proper Versatrak Synthetic Fluid (GM U.S. Part # 123878514, Canada Part # 88901045), adding 290 ml/0.6 pints of fluid.
8. Fill the transfer case up to the bottom of the oil fill plug hole. Note: this one must be full.
9. Install the oil fill plug and gasket. Torque the fill plug to 28 Nm/21 lb ft.
10. Lower the vehicle, if raised.

I just read your whole post and all you managed to copy and paste is a drain and refill. Now if you need to copy and paste how to remove a drain plug then you shouldn't be working on cars.

Well I got it changed. Boy that fluid really has a smell to it. The old fluid was sort of light brown. The new stuff is almost clear. It seemed to keep the rear from making the loud noise while parking but I still think there's a noise at highway speeds. Maybe the change of rotors/pads will cure that as well since I'm doing a break change.

I had to replace my rear end this spring as GM will not admit there is a problem with this rear end will not make a re-build kit available. From what you described, a noise from the rear end, could be the sound of the begining of the end for your rear-end.

I had to replace my rear end this spring as GM will not admit there is a problem with this rear end will not make a re-build kit available. From what you described, a noise from the rear end, could be the sound of the begining of the end for your rear-end.

groan moan from rear when turning could indicate low fluid level and/or need to change fluid in the AWD versions. clunk in the trunk sound more prevelant when going over bumps could mean rear knuckle bushings are bad. I haven't heard about other types of noises.

The sound I got mostly was not unlike a faulty muffler.

Well this car is acutally my in-laws. She's been complaining of rear noise for some time now. The dealer has replaced the muffler twice and the sad thing is the replacement one is louder than the original. She still wasn't happy so that's where I came in. I read about the need to change the fluid so that's where I thought I'd start. The change did make the "power steering type noise" from the rear you'd get sometimes while parking or turning real sharp. It seems a little more quiet but not sure if the remaining noise is the rear end or tire noise. She also had new Continetal tires put on it last spring. I guess we'll just have to wait and see.

You have to rotate the tires regularly on these things, a real pain. If there is uneven wear on either of the rear tires, it will burn out the rear end.

Did she get in on the recall last summer for rear ball joints? Long shot but may be part of the problem if she did not get that done.

Wheel bearrings can be a pain as well.

I dropped over 6k last year on mine, mostly on tring to find out my rear end problems were and then fixing them.

I don't know about the recall. I'd have to ask. No, the tire always wore evenly. It's just now on the 2nd set of tires.