Ford C350 Dual Air - Flush?

[slawson2000]

I was directed this way with my questions about a flush. Here is what I have going on:

https://www.autoacforum.com/viewtopic.php?f=3&t=12933

Is there a need? If so what could I use? Is appears most of the system will be replaced except the front evaporator and rear loop.

Thanks in advance.