1997 Chevy Blazer making strange noises

I have a 1997 Chevrolet Blazer 4x4.
mileage: 130,000 (approx)
V6 Vortec engine

When I am driving down the road the truck starts to make a humming noise. As I accelerate the humming become a high pitched squeal and gets louder. If I let off the accelerator the squeal stops.

As I start to decel and break it gets reall loud and you can hear a scraping noise and then at about 50mph I hear a loud clunk and the squeal stops and returns to the low hum.

What is the problem and is this going to put me in the poor house to fix?

Thanks.