None of it

1) They’ve contacted you three times, each time with a completely different amount.
2) They don’t get to determine where the money comes from. You list your assets. If this is the only asset you have the court is far more likely to garnish wages than to take the vehicle your husband uses to get to and from work.
3) You need to tell them the next time they call that you are formally requesting proof of the debt pursuant to the Fair Debt Collection Act.

Some of these collectors are legit and you really will have to settle with them. Others aren’t and it’s a scam. The higher the pressure and the more inconsistent their requests the more I smell a scam. The first ones will respond to your mention of the Fair Debt Collection Act, the second may not–but they’re not in a position to sue either.