Where to put some extra money?

4.3%

Another option is to put it in a high yield savings if it's for an emergency fund. If you rather invest it, then put int in a low fee mutual fund like VTSAX that covers the entire US market. Average returns over the last 100 years is like 10-12%. Again, this is for long term money (minimum 5 years) since the market can get volatile' over short periods.

If you don't have an emergency fund, ignore the rest and start and emergency fund.

Put it in a high yield savings account. Have the truck payment automatically pull from the savings account. You have virtually eliminated the payment but you're gaining a couple of interest points from the account an not pre-paying 0% money.

Take what you were paying on the truck and put it an index fund. DCA until you have enough in the index fund that combined with the leftover from the $30k and the little interest you earned you have enough for your next vehicle so you won't have to finance it.

Once that's done, you can keep investing in the index fund or pay extra principle on your mortgage. Not exactly paying off debt but using your money wisely and getting a fund so you can avoid future debt when interest rates might not be so favorable.