It may be a bit of a stretch in Arkansas, but $8K-$15K is what folks are paying on the left coast. (Literally, to a retrofit company actually called "left coast diesel"). If going the keep it stock route, the Ford dealer often hits 6.0 and 6.4 owners with five digit repair bills between $10,000 up to $18,000.
On the other hand, in 13 years, I paid a total of $15 for a cam shaft position sensor that I installed... in the glove box. That's it as far as engine repair. And truth be told, I haven't even needed it yet on the motor. I'm still on the original camshaft position sensor. Furthermore, I didn't even have to spend that $15, because Ford issued a recall beyond the original 5 year warranty. It just wasn't worth it to me to find the receipt and submit the paperwork for the reimbursement.
So, which do you choose?
An older engine with a well known $15. potential repair?
Or a newer engine with a well known $15,000. potential repair?
Even if it is only a $5,000. repair in states with a lower cost of living, the economics of potential risk is clear.