1989 ford f superduty 7.3 diesel
 

have a slight proablum. have 89 f superduty truck withe 7.3 diesel it was starting and running fine but today when i went to start and move it when you turn the key nothing happens the starter douse not engage or make any noise acts like ther is now power to any thing both battery fully charged and connected what should i look for any help appreatchiated thanks brian

When you turn the key to on do you have dash lights and gauges? May need to check that battery connections are clean and tight.
Also if you look on the pass side inner fender you should see the starter relay. You could jump the two big terminals on it with a wrench or similar and see if the starter then runs.
If it does then you may have a bad neutral safety switch (if auto) or bad clutch interlock switch (if manual). If auto try moving the shifter to Neutral and trying it.

1989 ford f super duty 7.3 diesel
 

got truck to startand run as it should but will need to replace the battery cables any body know of a good place to get the battery cables let me know thanks brian

got it running nut problum came back both battery's fully charged 13.5 volts per battery but when i turn key on no dash lights or any thing come on but if i turn radio on it works butif i push clutch pedale radio goes ought it acts like its not getting full power evin with to good fully charged battlries what should i look for thanks alot brian:-huh

Not good on electrics but maybe take the lower steering column shroud off and check that the rod that connects the key switch to the ignition switch is moving properly when you turn the key.
Also there is a big bunch of wires all connected to one big terminal on the fender mounted starter relay, some are fusible links, check that they are good.