What about DC-8 Super 70s? 110 were "made" or converted and were used in both passenger and freight service by big name airlines and freight companies; For those who dont know DC-8 Super 70's were DC-8 60 series that had CMF-56-2 installed at a cost of about $12 million per aircraft.
"The Super 70s were about 70% quieter than the Super 60 Series and between 18% and 25% more fuel efficient than the JT3D, depending on the model"
DC-8-71 - range of at least 4100nm a fuel burn of 8300 kg/hr FAA certification on August 15th 1981
DC-8-72 - range of at least 6070nm a fuel burn of 7060 kg/hr FAA certification on September 17th 1982.
DC-8-73 - range of at least 5860nm a fuel burn of 7320 kg/hr FAA certification on June 23rd 1983
those are going off the conservative numbers, they also had decreased take off run and all models would then qualify for Chapter 4 certification. It was reported that all versions of the aircraft gained at least a 40% increase in usable range but were still limited to 60 series operational limits. I would think these would be an easy update to incorporate much like when you can install hush kits for certain aircraft.
http://www.airlineratings.com/news.php?id=187http://tonymadgehjg.proboards.com/thread/8139/dc-dedication-first-last-v2
