and higher-GVWR 4400 were introduced as replacements for the previous 4900 model series. In 2002, the lower-GVWR 4200 was introduced as the replacement for the 4700 series, marking the introduction of the VT365 engine. In 2006, the 4100 was introduced, expanding the model line into the Class 5 segment; the model was discontinued a single year of production. The 4200, 4300, and 4400 were produced in both a standard and low-profile frame. The 4400 was also produced in a semitractor; sitting 4 inches higher than the chassis truck, the 4400 tractor was the only version offered with the DT570 engine as an option. Brand revision For 2008, coinciding with the introduction of the International ProStar and International LoneStar, Navistar revised the branding of its truck model lines. In line with nomenclature previously used by International Harvester, truck lines adopted a "xxxxStar" naming scheme, with the 4000 series adopting the DuraStar model name. This change was completed in its entirety for the 2010 model year. In another revision, to comply with 2007 emissions regulations, the powertrain lineup underwent extensive revision, with the 6.0L VT365 V8 replaced by the 6.4L MaxxForce 7 V8. The DT inline-6 engine family underwent revisions as well, with the DT466 becoming the MaxxForce DT and the DT570 becoming the MaxxForce 9, adopting four-valve cylinder heads and exhaust gas recirculation to reduce emissions. While each International model series retained the use of numerical model codes, after the model revision, their usage was highly downplayed, largely relegated to places such as the build plate for the vehicle. Externally, International replaced the numerical series and engine identification with script identifying the model series. In 2010, the International TerraStar model line was introduced, effectively replacing the discontinued 4100 model line. Sharing the cab of the DuraStar, the TerraStar sat on a lower frame and wore its own hood. Powertrain revision For 2015 production, the DuraStar began to phase in Cummins ISB6.7 diesel engines as an option, slotted in between the MaxxForce 7 and MaxxForce DT, with the ISL as an option alongside the MaxxForce 9. Although Cummins ISX engines had been offered in International Class 8 trucks, the expansion marked the introduction of the first selective catalytic reduction diesel engine for a medium-duty Navistar vehicle. After 2016, Navistar ended production of the MaxxForce 7, MaxxForce DT, and MaxxForce 9 engines, with the ISB and ISL engines becoming the sole engine offerings