They are supposed to be carriage head, I think.
So I'm now on to the deck belts, when I spin the middle blade should the other 2 also spin? I tried removing the top cover on the deck to get to the inner belt but once the nuts get to a certain point the whole bolt spins, I flipped the deck over and the bolts are a non head flat type bolt, no way of grabbing it, so how can I get hold of that bolt?
Spray them all down and let the nuts soak with penetrating oil.
I use a rotary grinder to make a flat blade slot to keep it from turning. Go to regular bolts for reassembly. They hold a little more grass, but as long as you wash it all out, you'll be fine.