Interesting. My GT (no Perf Pack) has Conti Pro Contact RX. Wonder what the differences are between TX and RX. I looked at Tirerack but cannot really tell.
https://www.ford.com/cars/mustang/pricing-and-incentives/
Go to Pricing and Incentives and Purchase and Estimate Payment. The interest rate will be displayed according to the length of the loan. Also the text below that says valid until 4/2/24