1988 Chevy Truck Truck won't start

The Truck for a while was having difficulty starting, we initially thought it was the battery because if we jump started the Truck it would run. I've hooked up the battery, charged it, and taken it down to the local auto parts store and the battery tested good. Now, once we put the battery back in, the truck will click once, but will not turn over. I'm thinking starter or solenoid. Am I going in the right direction or could there be something else going on? Also, If starter where would it be located on a v8 305, I think it's under the engine block on the passanger side, but haven't had the chance to put the truck up on blocks and really look for it. Any help would be appreciated. Thanks!