Double check the battery terminal bolts. If they are a little loose or have a little corrosion on the poles then that could be a prob. Also look at and wiggle the wiring harness at the - terminal. Lotta wires all going to the - terminal sometimes have probs where some of the tabs join into the main conductor, they can fatigue or corrode. This has made big probs for me in past.
Of course you put the wires on the alt back correctly!!!!! Failing alt connection probs or mega fuse probs, perhaps the new alt is a dud.
