My rear end is leaking (differential,third member, R-180). I noticed that it is coming out of the vent doo-hickey. When I filled it I made sure not to over fill. Is this a common problem? Any suggestions on how to make it stop?

Keep it down to the legal speed limit and it should stop leaking!

They all leak a little, but will be likely to leak more if you are driving higher speeds and/or if the fluid level is too high. Did you fill it with the car level or with only the rear up in the air? This is typically not something to be concerned about. If yours is leaking heavily you might want to put a long tube with a catch can at the end. Lots of racers do this to keep fluid from leaking on the track. Not a bad idea to check the fluid level once a year. If you drive the car hard wouldn't be a bad idea to change the diff fluid once a year or so as well. Same goes for the trans, breaks, coolant oh and engine(of course this should be changed more than once a year if hard driving).

Have fun!

I was going to say it sounds like you need a proctologist :classic:

I race with a full welded 4.11 R180 using synthetic lube and have never had a problem with any leakage. I don't run a catch can either. The only thing I can think of is what Royce already mentioned - was the car level when it was checked and filled?

Boy, you guys are brutal. ()LOL I went and checked the oil level and it was still full. So I guess it WAS overfilled. This time I made sure the car was level. And replaced the old with some new synthetic.:classic: