I recently bought a 72 Mustang. The owner said the differential was possibly overfilled. I just pulled out the filler plug and about 3/4 quart of oil came out. He said he filled it through the axle thinking there was a leak in it. He got the car as a trade and sold it within a month of getting it. I’m wondering if I can just plug it back up and be done with it. It has been leaking out of the drum brakes so probably need to clean the brakes out?