I’m not going to send you to this site but if you need previous versions of the iPod firmware, it’s all right there for free. There might even be current versions. Just saying.
I’m also not going to tell you to shift-click (PC) or option-click (Mac) in iTunes when you click Update or Restore and select the ipsw file you’ll download. I also won’t encourage you to wait a little while and then smile like the cat with the canary.