My car has been sitting for almost a year.

I go outside get it started & start checking everything when I see that the master cylinder is empty in the front section. I know I have an leak somewhere in the brake system but does that mean it's somewhere in the front by the front section on the master cylinder being empty. I'm just trying to figure out where to look for the problem.. I checked both calipers, wheel cylinders & along the frame to see if I could find a leak but I found nothing. What could be the problem here?

 

I think the two brake systems actually run in an X pattern, left front with right rear, and right front with left rear. Check the rear calipers and lines.
If you can't find a leak, fill the reservoir and drive it a little, then if it is still leaking you will have fresh fluid to find.

 

Not on that car. It's a strictly front and rear split.

 

I drove the car around for a while then let it sit on some cardboard while i was at work. When I came out I found the leak along the drivers side frame under the door going to the rear brakes. The front section of my reservoir was going empty so that means the front section is for the rear brakes & the rear section of the reservoir is for the front brakes. Also I bled the front brakes and I had to add some fluid to the rear section so that confirm what I just said

 

More than likely, the line from front (master/prop valve) to the rear tee rusted through. I had the same problem on my 77 after sitting 24 years (although mine blew mid smokeshow!). And yes, front, small resevoir is for the rears, and the rear, large resevoir is for the fronts.