You can rebuild it for about $10 if you just want to buy the contacts inside the starter... . which is all that is really wrong in there. You can change up to 3 sets of contacts before the plunger is bad... . which is why you spend $30 at that Diesel Electric place in AZ... . they give you two contacts (~$5 each... and at that they are making a nice profit)... and a plunger which takes up the remainder of the cost... .
The starter is really easy to pull... . use a 10mm 12-point wrench that is a bit lengthy as the bolts may be on tight... then use a shorter 10mm 12-point to move them out the rest of the way... . the electrical connections are self explanatory... . 8mm, and then 18mm... if my memory is worth it's weight in PSD parts. I ended up cutting the big red insulator on the heavy gauge wire as it was a huge pain in the butt to get things back together with it being its non pliable self. Do the electricals first, then remove starter... . then rebuild starter... . then reinstall starter... . then do electricals again.
Matt - been there, done that... . got the T-shirt... . truck has shut down every time since I changed out both contacts.