Front differential drained fluid?

Hello,

Drained the fluid then fastened plug. Opposite that is the overflow plug I left open. On the passenger side there are two m6 Allen head plugs. I removed the lower one filled until fluid started coming out then closed. Removed the upper one filled until fluid started coming out then closed. In all this time no fluid came out of the overflow plug the car was level. It took about 1-1/2 quarts.