I have some new parts, no longer usable to me, that I put in the classifieds.

Is it OK to post they are listed up there? In the appropriate forum, of course.

 

Nope. That would be the same things as posting a classified ad in the forums. The purpose of not permitting them on the forums is to avoid one-to-one conversations, like "what kind of condition are they in" or "how much are you asking" that are best left between you and the buyer in a private conversation. Announcing you have put something in the classifieds will simply result in a thread discussing the items, which is what we aim to avoid.