95 Caprice Power Loss

I have a 1995 Chevy Caprice classic 4.3 lt Engine. The past few days the cars battery gauge started dropping the power was cutting out but no all the way just down the back up. I assumed it was a battery problem, just replaced today but the car still has power loss. I just can not come up with the answer to fixing this problem if any one can help thank you.

I'm thinking the Alternator (http://www.autozone.com/N,16400086/shopping/partTypeResultSet.htm) but unsure if it really is.

Test alternator output with a load tester.