Found washer in drain pan, diff or tranny?

Sigh, I changed rear and front diff fluid, as well as manual tranny. Found this washer in the drain pan, which does it go to?

 

Crush washer, should be one on each diff drain plug.

It’s a good idea to replace those with new ones when you change diff fluid.

 

If none of the three leak, no worries.

Otherwise, it goes on the one that leaks....

 

Each drain plug you removed has a washer...pretty easy bro process of elimination....

 

Yup, it's one from the transmission. There are two types of gear oil plug washers, well three if you include the huge copper one on the front diff.

 

The one on the left looks like what I have, it's more flat instead of rounded. I also did the transmission last.

 

Trans isn't a crush washer I don't think. Diffs are and drains plugs should be replaced. I didn't do the fill washers though.

 

Shh, keep it secret. Now everybody wants one.

 

They're both crush washers, the left one is softer aluminum the aluminum in case and of course softer than the steel plug. The steel ones have a domed shaped that distorts but the aluminum ones just squish out a little. They probably could be reused a couple of times but they're cheap, I just use a new one. The steel ones can't be re-used, they go from a domed shape to a flat shape.