Overfilled diff with fluid. Did I f*** it up?

So my 93 pickup has a slow leak in the rear end. The gasket for the cover has gone bad, but like I said its very slow like it doesn't leave marks on my driveway. So I bought the truck at the end of feb so I figured today that ill top off the diff fluid bc I'm too lazy to put a new gasket on. So I fill it up and I read somewhere that you fill it to almost full. Well it takes the entire quart of fluid so I figure "I need to go buy some more. But its better now then it was before so its okay to drive." I drive it to school and back and park it on my driveway. About 2 hours layer I come out to go to work and the driver rear tire is sitting in a pool of diff fluid. I'm assuming that I obviously put too much in being too lazy to check the correct amount to fill it. So did I Fuck the seal on that side of the axle? Or is it just gonna empty until its at the correct level and I'm okay?. And how much is the part. I've taken toyota axles apart a few times so I should be okay to do it on my own. Thanks!

 

If you've taken axles apart, you should be able to answer your own question.

Quite frankly it could be a myriad of things.

Your diff breather is clogged.

You overfilled the diff and fluid traveled to the ends of you axle tube, leaking out behind you brake backing plate.

If your breather is plugged, and the additional fluid / heat expansion pushed it out past the lip of your axle seal... I'd venture to say that it's been compromised.

Check your pinion seal, too.

 

A diff is kinda hard to overfill, since you fill it to the level of the top drain hole.

I'm guessing you had a bad axle bearing seal all along and the diff oil's been sitting lower than the failed seal. Once you filled it past that - it ran out via the axle housing to the wheel hub and onto the ground.

 

This sounds like the most likely, however a bad breather could cause it as well.

 

Damn alright. Thanks guys. I'll check my breather and order the seal.