I think part of this is also due to the emissions on new diesels. When DEF was introduced, it seems like the prices of the 7.3's, 5.9's and the like went up substantially. Even the 6.0 fords got a huge bump. I paid $24k for my 2000 7.3 CCSB in 2001... 2001... Between monetary devaluation, inflation, emissions… the older trucks are just a better buy for some.That difference in resale value is well known, especially as the trucks get older. Go look at the older (circa 2006-2007) 3/4 ton diesels...they enjoy a substantial resale advantage over their gasoline counterparts, even though some trucks from that era were not well built.