I would try taking off the battery cables, clean them as well as the battery terminals. Check the condition of cables where the wire meets the connection as well.... look for any green death. hope some of this helps.

Doc here,docvette said:Doc here,imp:
Check where the power comes together at the starter, at that same bolt there should be another wire that goes to the main fuse buss or the horn relay or the regulator (If External) on that wire, might be a fusible link, and it might be open..check there.
If all is good, carefully jump the Big bolt to the "S" terminal, (closest one to the engine block) on the solenoid, if it cranks over, Your starter and starter power system are whole, check the neutral safety switch for an out of adjustment or in-op condition.
Docimp: