I understand, I just have alot of parts, not sure who needs them, never sure what i need.
When you have a need, post up in Wanted, and ask what the other person wants in trade.
If you want to trim your inventory, use the Parts for Sale, with all the requirements. That doesn't preclude you making a trade deal with another member instead of exchanging cash. It just means you have to post a price.
It's worked fairly well this way for 8 years.