Need Help no 4x4

[Biggs85]

I have a 2004 F20 6.0L when I switch to 4h or 4L the lights on the dash light up, you can feel it click in the transfer case but nothing happens to the front they wont spin. I have Taken off the wheels and inspected what I could see and tried to lock the hubs manually and still nothing does that mean that I need to replace the hubs if so where can I find some cheap I don't care if they are manual for now I don't have to have shift on the fly.

Please help I don't want to need it and not have it cause the snow will fly soon.