All depends on what part of the country. Maintenance, and proof of it is greatly going to determine value with that many miles. Right now diesels are selling for way under KBB, where as three years ago you couldn't buy one for close to KBB, I wouldn't give more than 5 grand for a truck with 268K when there are way to many out there for half that amount of miles for 8-10K
Just my opinion!!
NCH