I've Got No Brakes!

[Matador]

Alright-

I was greeted to a little surprise today. I have a 1987 R10 (305/700R4). The brakes always pulled a little to the left, but it wasn't that noticeable. The truck has been sitting for about a month.

I turned it on today, and shifted to Reverse. The Red Brake Warning light on the bottom of the fuel gauge came on. I moved the truck backwards, at about 5-10 MPH. I hit the brakes, and really had to push them for the truck to stop. I then carefully drove down a road stretching on our property. I reached about 15-20 MPH, and then went to stop. The pedal gave me no resistance until I hit the end of the pedal travel. Then, the truck started slowing. It wasn't slowing as much as it should, though. I've made panic stops in that truck before- mashing the brake will lock the tires every time. This time, though, the stopping seemed leisurely at best.

Any ideas where to start? I've never done brakes before, but it looks like I need to now!

Thanks for the Help!