drained & filled my rear diff (11.5 AAM) today, but my driveway is uneven, going down hill sloghtly to right when looking at rear end. I put in 4 full qts, and it was about 1/4" below fill plug. Did I add too much?

Four quarts is what I put in, just to bottom of the fill hole.

yep,just fill it to the bottom of fill hole ,then stick your pinky in ,it should be within 1/4'' to the hole

i thought it was 5qt

i thought it was 5qt

From what I've heard the 11.5 AAM (diesel trucks), are 4qt.

After driving with new oil, and getting it hot, I opened fill plug to check level, and it started gushing out. I quickly retightened. I was on an up hill though, so I'm assuming its normal for it to come out of fill plug on that grade.