Turn the key but NOTHING happens. battery ok.

hold the key to start position and have someone tap the starter.

Sounds like a bad starter relay or starter or the connection at either of these locations could be bad.

This is going to sound strange, but I have to ask - Is it in PARK?

ck the shift linkage to the trans

There should be a small black wire going from the battery to the starter motor. It sounds as though it has come loose.
Check it and re connect it.
I hope this works.
Good look

run scanner for trouble codes, some auto parts stores   will do this for free,check fuses, check for fuel at fuel rail, if not check fuel pump relay, you should here it click when key is first turned on, if not try to bend tabs slightly to make good contact, if no click, replace relay if so turn key off then on listen in tank with cap off for whirling sound if tank, if not could be fuel pump, sorry 

sounds like starter is bad have someone crank while you tap on starter see if it spends over if so starer no good.also those trucks had problems with the battery cable going to starter corroids.good luck.

have battery load tested at locale auto parts. you may have a bad cell .if ok sounds like a selinoid problem

Check list of things to do;

1) Does the headlights work.
2) Is gearshift in PARK or NEUTRAL. Wiggle gearshift slightly while starting.
3) Check the fuses. ( these are typically located inside the car)
4) Check the fusible links. (these are typically located under the hood)
5) Check ignition switch. (does it turn on radio ? will alarm sound if driver door open ? etc)

It could be the park/neutral switch, next time it doesn't start try wiggling the shifter in park while turning the key, or shift to neutral and see if that will work. if that doesn't change the problem I would replace the ignition switch.