Seems it's recommended to replace all those plugs when replacing fluids.
Could not find them online, for my 2007 GL450
Called a local MB dealer, here is what I found:
drain & fill plugs for front & rear differentials are all the same. the plug comes with gasket on it. price: $12 each.
drain & fill plugs for transfer case are the same, $15 each. corresponding gasket is $7 each.
therefore all eight pieces cost about $102 after tax at local MB dealer.

lol this is more of MB dictating to replace because why not

If it leaks after reuse, then replace. I'd be inclined to just replace the washer, anyway. It's not like the the plug and washer are holding back some enormous pressure. You tighten the cap on a milk jug, right?

Just don't torque the heck out of the plug when installing. It simply does not need to be that tight.

that makes sense.
if the plugs are highly corroded maybe replace all of them. otherwise they could be reused.

Agree with using new plugs and washers. For sure washers. Plugs could be reused if not available for whatever reason.

I`m exactly in the same boat, bought the diff fluid, have the little pump ready, just waiting for the good weather, I checked everywhere online, no luck, stealership was the last resort but after seeing those prices, nope, nada, thanks.
I`ll go with changing the washers and keep an eye on them for a couple of weeks. Should be good to go.

To each his own. If it makes you feel better to install new, be my guest.

Me, I'm an engineer and strive to do things as lean as possible. Heck, even if I were given the plug and washer free I'd only install them if the old ones leaked. I'd keep the new ones in the inventory, just in case.

A little trick I learned from AvE: Copper crush washers can be reused; it helps to anneal them. Copper work hardens, so the action of compressing them stiffens them. Heating and slow cooling re-softens them.

The washers for transfer case plugs are available in amazon. Search 16-20-1.5 copper gasket. The differential plugs I heard don’t need gaskets. Just some Permatex 82194 Ultra Grey Rigid High-Torque RTV Silicone Gasket Maker would be enough.

No sealant for the plugs.

Correct that the axle plugs do not use sealing rings (crush washers).

I bought new ones fron the stealer but they only had 4 so I reused two as as I was doing both diffs and the transfer case. I reused two for the fill plugs only and haven't had any issues. They are all the same for front and rear diffs as well as transfer case. Don't forget to remove the fill plug first!

Not the same for the transfer case. Tcase uses a sealing ring (crush washer). Axles do not.

yes that's what i heard from the MB dealer. The parts agent actually said the MB dealer usually replace just one plug for each differential.
while many youtubers e.g. the famous "iRepair Autos" replaced all the plugs in their video.
plan to pick up the plugs today and also request the torque spec while there.

Yes this is correct. My mistake- I bought TC plugs first and did that and then later they had only 2 plugs available for the diffs.

TC plug and dif plug side by side. They are almost identical. Just different material finish. The dif plug comes with oring on it.

Not identical. Look at the machined shoulder on the axle screw vs a relief cut on the tcase screw. No one should attempt to use these interchangeably.

That’s correct. They have different part numbers.

What’s the torque spec for these plugs. A quick search shows 50Nm. That’s probably good enough.

See the DIY in my signature: https://mbworld.org/forums/gle-class...ml#post8345443

25Nm transfer case plug
35Nm front axle plug
50Nm rear axle plug

The differential plugs use o-rings. I wouldn't attempt reusing the o-rings, especially after they've been twisted and crushed. There is nothing associated with the differential plugs that is normally called a washer.

The transfer case plugs use crush washers, which are always replaced.

Was able to change the front diff today.
Used LiquiMoly 85-90 as replacement.
It was a little more than a liter. Used Permatex Gray on the same plugs.
Cleaned the area well, I’ll keep an eye on it this week.
Will do the rear one next weekend.

This from the rear, I used Valvoline 75W90 for the rear. Used Permatex gray again on the plugs and torqued them to spec. Front plugs are so far so good, about 5 days now.

Part numbers please?
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I dont have the part numbers but they are cheap enough at the dealer if you have one close by. I recall paying about $4 each from memory.

yes I got mine at a local MB dealership.