Intermittent no start problem

[Kixwy2]

Recently my truck has been giving me issues when I try to turn it over - I turn the key but nothing happens. Zero. Dead. Silent. Since I just dropped a GM crate in it, I also replaced a bunch of the peripherals. Distributor, wires, cap, module, battery cables, starter, etc. I thought it might be a hot start problem, since a couple of them were right after some short trips to the store, but the other day I tried to start it after it sat for a day, and I got nothing on a cold start.

I check all my connections and everything seems solid. I even went under the engine to check for any shorts or cut wires from road junk, but came up with nothing. When I put the negative battery cable back on and tried again, it fired right up like nothing was wrong.

??? I know that cable was tight, too when I pulled it off. Any thoughts or ideas?