No Crank?, No Start!

My '97 F-150 sat for about 5 or 6 months with a dead battery. The other day I
got a free replacement. When I tried to start the truck it would make one loud
knock. Thinking that the issue was the starter I took it out and had it tested at
autozone. They said it is still good. So I decided to clean it before putting it
back in the truck. I then decided to rebuild my starter and add new grease to
the gears. The brushes are not perfect but they are still good. I took out one
of the brushes because there was a small fragment of the brush stopping it
from pushing back out. Once everything was all clean I proceed to to
reassemble it. I took it back to autozone to make sure it still worked. I put the
starter back in my truck and I still have the same issue. When turning the key
I get one loud knock.

Thinking something could be seized up I took off the belt and checked all the
pulleys, A/C, Fan, Alternator and Power Steering. They are all good and spin
real well.

I than got worried and proceed to rotate the engine by the harmonic
balancer. Again, all was fine. Thinking maybe rotating the engine would allow
it to start I tried and still get the loud knock sound.

By the way, When I put the starter back in my truck I noticed what looked like
a Grounding strap missing the bolt hole hanging down next to and just above
the starter.

Any ideas or suggestions?

Oh and I did see a sticker about an anti theft system that will not allow the
truck to start if tripped. But if this was the issue wouldn't it not give any power
to make the click to start with?

Thanks, Mike