Need help 07 6.0

[nathaniel11]

I could really use some help right now I have been scratching my head on this one.

So I replaced the altenator about two weeks ago everything ran fine the batteries charged up well the otherday the battery light came on again and a few more miles down the road the truck completly shut off. Well I brought it back and got another one under warranty and it is still doing the same thing I cleaned all of the connections to and from the battery and altenator.

Am I missing something?