My 73 f100 has no brake booster should it? I am having problems with a hard brake pedal and only about half brake power. This truck did sit for years before I bought it .

 

Power brakes were optional in '73.
I would go through and check the entire brake system to be sure but manual brakes of yesterday are going to feel different than modern brakes.
If you add power brakes to the F100, you need to get the entire pedal assembly, the bell crank assembly that mounts the booster to the firewall and the booster/master cylinder.

 

1973/79 F100 2WD: Manual disc brakes were standard equipment, power disc brakes were optional.

 

What would be the most likely cause for hard pedal and half break power .The front has discs

 

You said the truck has been sitting for a while. You need to pull the wheels and check the brakes.
My first guess would be the calipers or rear wheel cylinders have frozen from sitting.

 

Thank you all. Will do it this weekend when I do the shocks

 

The two pistons inside the MC could also be seizing inside the bore.

The inner linings of the flexible brake hoses can also break down and slough off over time and act like a check valve --either impeding brake fluid pressure/flow to the calipers or, allowing pressure/flow to them but slow about releasing the pressure, after you get off the brake pedal.

Out of curiosity, is the brake warning light lit up on your dash?