I bought a 1987 F150 that is not cranking or even clicking...I changed the battery, changed the starter and changed the solenoid...and it wont even click, but the dash gauges work, lights work....please HELP....any ideas what it could be or what I can check next?

 

With all the parts you've thrown at it, what have you TESTED, and what were the results?

Automatic or manual transmission?

 

The starter and battery were both bad, so I changed both of them out and changed the solenoid as well, it is an automatic...

 

Try starting it in Neutral. Also try moving the shifter from Neutral toward Reverse and toward Drive, but hold the key in the START position at the same time.

 

Are you getting power to the starter solenoid when you turn the key?

 

Ditto to what Lead Head said.

Odds are this quick and very simple test would have saved you the cost of that new starter & solenoid

The wire from the ignition switch to the starter relay/solenoid is probably red/light blue stripe & probably has a slip on rubber boot.
Remove the boot & jump 12 volts to that pin. Does it crank? Be sure it's in park when you do this & leave the ignition switch off.