Car wont start .

[69bananabeast]

'75  440 .    Car wont crank over inside the car , but will crank from the the starter relay.  First thought the starter might have been hot or the gas might have been , but no dice .  Any one got any ideas wat I should do next ? 

[Bandit72]

my guess is neutral safety switch...

later 

[Plumcrazy]

When you hold the key in the crank position see if you have power in the yellow wire at the starter relay.

[WINGMAN]

  Do you have power inside the car, dome light dashlights? If not can be the fuse link wire at the starter relay.    JR.

[69bananabeast]

everything else has power , it just wont crank

[mikepmcs]

my guess is neutral safety switch...

later 

I agree, try this first cause it's the current that flows through this switch that goes to the starter relay/solenoid, which then allows the high current flow through the battery cables to the starter. same switch also controls your reverse lights i'd bet. are they working?.  maybe try to move your shift lever like say to neutral and see if it kicks over then.
here's a picture.

[BigBlackDodge]

Connect a ground wire to the starter relay, where the neutral switch from the tranny plugs into.................turn the key.

BBD