the is no bus junk yards around here
Except for the body work, for the most part, a bus is a truck. Get to know the local truck parts guys and mechanics (the old ones, not the parts changers or the "If it ain't in the computer, It never happened" guy").
If there is a truck wrecking yard nearby they can also be a lot of help. Don't go in and say "I have a bus" .Take the part with you and say "Do you have something like this?" There again,IMHO older yard, older guy is better. Note: Old junk yard guys may have the same disposition as their dog.