Truck Repair: starter, starter relay, test light

Question
i only get a click when i turn the key i have all new batteries and alternator .do u think its the starter and how hard  are they to replace ?I have a 99 kw t-2000

Answer
It is either the starter relay or the starter itself.  If you are getting power to the switch leg of the starter, then the starter is bad.  To check the switch leg, look for the single small wire on the starter sylonoid.  Have someone turn the key to start and if it has power (use a test light) replace the starter.  If it does not have power replace the starter relay.