Converting a 2003 2wd to 4wd

I have a 2003 and 2004 tahoe that i need to convert to 4 wheel drive does anyone know either how to do it or if its even possible.

The best way to do this is ------ sell it and buy a 4WD!!

Honestly

-slacker

Its possible,,,, but,,,,,,,,,,,,, but,,,, slacker is right,,, you'd be better off buying a 4wd....