Rear-end weight difference

I saw no decrease in 1/4 mile E.T. going from an 8 1/4 with 3.21's to an 8 3/4 with 3.23's. The rear is a good bit heavier but the gears will way more than make up for it. I went from 17.15 in the 1/4 to 16.90 in the 1/4 by swapping out my 7 1/4 w/ 2.76's for an 8 1/4 w/ 3.21's.