Rear end on 76 Newport

Hello all,
I have searched the forums and found some info on the right rear gears/ratio to get to spice up the newport. Its a 400-2 and will be sporting an edlebrock 1406 and likely a stock 4 barrel intake (as i have one on my bench). I have the 8.25 rear and 2.76 gears at the moment. I am not sure what case I have, how can I find out?

Also opinions on where to get the gear kits from (what brand) would be helpful as I am on a budget, and would buy used if the...

Rear end on 76 Newport