Jerry, you know the answer to that. A photocopy of course. If they agree, in writing, to replace the check then they would probably want the original back at which time you can provide it to them...
If it was an overpayment they would have stopped payment eventually. Unless you know for sure that it was, I would go ahead and try to get a new one issued. Tell them you put it away and just forgot
Wow Jerry, you must be a wealthy guy. Hold that check for 6 years and now thinking you won't even bother to see if you can get it paid? The advice of the Credit Union is of course what you should do.
Greetings Joyce, Before I respond further to your question, I must make clear that I do not represent you, and cannot give you individual particularized legal advice. No attorney client relationship
The short answer is that a lot depends on the homestead and exemption laws of the state you live in. But the longer answer is that usually the homestead is the most generous part of the exemption laws