Transfer box questions

When I got my tranny fixed, my transfer box was rattlying. Then for weeks it has stopped. Is there any sure way to tell if your transfer box is
going bad? How much would a trnasfer box cost from a junkyard?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
Add image file
Upload is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.