I used to be able to the z plan thru my dad (former Ford employee) and then my mom until she died at age 94. I always took it as getting a new vehicle, taxs and fees free. Meaning what the sticker price was, was about the price I paid at the end.
The clunking noise might be a bad strut. My brand new 24 badlands had a bad strut from the start. Made the clunk noise going over sharp bumps, pot holes or sewer covers. Took 2 visits to the dealer before found the issue. Even though I told them either something is loose or a bad strut.