I know this doesn't happen too often but enough to possibly warrant a solution.
I wouldn't normally think it's a big deal for somebody to ask if a part is still available. I've done it. But for a thread that has had no response in a year and a half?? If we could set up an auto-locking system of threads in the for sale section, it would greatly reduce clutter and useless bumping of items.
To be fair with sellers, the locking feature would only restrict posts without activity in the past 8-12 months. An active seller will bump threads enough to prevent a lock of the thread.