Battery light was coming on then shutting off. I thought it was the alternator originally but I took the negative cable off the battery while the truck was running
And it kept running. I tested the battery while it www running it was11.4 on the Meter so I replaced the battery. Next day after driving about 10 miles the light came back on. So any ideas possibly still the alternator ?

 

I'd be willing to bet on the alternator as your culprit.If its coming and going its likely a brush issue.If you lose the rectifier or regulator its gone and doesn't come back. A somewhat crude but fairly effective test for brushes is to catch it in while its in no-charge mode (light on) and give the alternator case a couple raps with a hammer. If the light goes out you have your answer. Ultimately this diagnosis is moot since all the above mentioned components are located inside the alternator anyway. 11.4 volts running is NOT charging. Unless the battery had a dead short, a working alternator should be putting out about 14 volts.

 

The correct test would be taking the positive cable off the battery while the truck is running. If the alternator is bad, the truck will die. Go give that a try and see what happens.