I have found two ancestors in naturalization indexes, and the New York court files provide 3 different numbers. I'd like to avoid spending an extra $20 on having USCIS do the lookup for me.

There's a 7-digit typed number on the top of the card, a six-digit hand-written petition number, and another (different) 7-digit number on the bottom of the card.

Which one should I use?

Thanks!