[mels80ga]

I will be putting a Ford 9" rear in my car in replace of the 7.5 10 bolt and I was wondering if anyone could give me an idea of ET change to expect. Let's say with all things being equal, other than wt. and parasitic loss of the 9", will there be a noticeable amount of power loss? I would guess about 50 lbs. of wt. change, I will weigh everything when I make the change. The 10 bolt had a 3.73 gear and I would like to get an idea if the Ford rear had a 3.73 also. Here's another point to ponder, the new rear will actually have a 4.56 gear. Anyone have experience with this type of gear change?