Driving down road everything went dead, wouldn't start. Boosted it, ran for a few minutes and died again.

It all started when the battery light came on while in town. I started home and got within a block of home and the dash went blank and the truck died. I got a jump, but the truck would not stay running. I let it charge via jumper cables for a few minutes and it started and I drove it home. The next day it would not start. I figured it was the battery so I bought a new one. The truck ran great for 2 days then would not start again. I'm thinking it is the alternator. I'm dreading replacing it.

truck continuously ,will not start,changed all major components ,(battery,starter,alt.)power drain from somewhere? had all systems checked.