For 70s-80s gm truck guys...82 k5 Blazer - Electrical issue

[vortec]

Friday night, my 1982 k5 w/350 ran great. Drove my other truck, saturday. sunday, the blazer wouldn't start.

what i know:
-battery voltage is fine, and BATT terminall on fuse block reads same.
-things i've installed myself that bypasses the fuse block, such as my fog lights, and power port work fine. (the circuits are fused individually)
-headlights/taillights, starter, dash lights do not respond.
-all fuses in fuse block are fine.

at first, when it wounldn't start, i thought bad neutral position switch or ignition switch. neither problem would affect the headlights, though. since they are dead, i'm looking for a problem with the hot lead or ground for the fuse block. i felt stupid, yesterday, when i found the wire i thought fed it did not. i'm working in the dark, with a maglite, since i get off work late, and i haven't replaced my droplight yet.

i don't know how the heck sitting for 24 hours killed my truck. if anyone has diagrams of the fuse block or advice that could save me some hassle, i'd really appreciate it. thanks. at least this isn't my dd, thankfully.