My 1977 f150 custom seems to be draining it's battery overnight. Someone told me it might be the ignition switch that needs replacing. Thoughts? Suggestions?

 

First try unhook battery after parking it for the night. Go out early next day test the voltage... Then hook it up and see if it starts.. If not its the battery... Next thing is to remove all fuses from the truck and see if battery goes dead... If it does then it is not a fused circuit thats the problem.. Now if it does not go dead then it is a fused circuit. Using a multi-meter have some one help you and set teh meter on amps and test the load.. No fuses load should be about 0 now replace fuses one at a time until you see a jump in draw from the batttery, thats the circuit your having a problem with.. This is my best guess things to try...