1960s to the early 1990s. The rear suspension was a live rear axle with rear leaf springs. For the 2008 model year, the chassis underwent its largest revisions of the fourth generation. In an effort to improve handling and safety, larger brakes were added, improved steering, rollover stability control, and a higher GVWR. The twin I-beam layout was retained, making it the second last Ford vehicle to use it. Powertrain At its 1992 launch, the fourth-generation carried over its powertrain line from the third-generation model line (sharing it with the ninth-generation F-Series). A 4.9L inline-six was standard, with a 5.0L V8, a 5.8L V8 offered as options. On 250 or 350-series vans, a 7.5L V8 and 7.3L Navistar diesel V8 were also optional; the diesel became turbocharged in 1993. During 1994, the IDI diesel was replaced by a 7.3L Ford Powerstroke diesel V8 (also sourced from Navistar). For 1997, the E-Series underwent a revision of its engine lineup, retaining only the 7.3L diesel. Sharing its gasoline engines with the tenth-generation F-Series, a 4.2L V6 replaced the inline-6 and a 6.8L V10 replaced the 7.5L V8. The 5.0L V8 and the 5.8L V8 were replaced by 4.6L and 5.4L V8s, respectively. For 2003, the 7.3L diesel was replaced by a 6.0L diesel from Navistar. While gaining an intercooler over its predecessor, due to the lack of airflow in the engine compartment (compared to Super Duty trucks), Ford had to detune the E-Series version of the 6.0L V8. For 2004, the 4.2L V6 was dropped and the 4.6L V8 became the standard engine, making the E-Series the first American full-size van with a V8 engine standard. The 6.0L Power Stroke was offered until 2009 in the Ford Econoline vans (model year 2010), even though Ford Super Duty trucks were upgraded to the 6.4 version in 2007. Diesels were no longer offered after the 2010 model year. For 2009, the E-Series gained flexible-fuel capability with 4.6L and 5.4L engines (allowing them to use E85). In May 2014, the final 4.6L V8 was produced for the E-Series, with the 5.4L V8 becoming the standard engine for 2015. For 2017, the 6.8L V10 replaced the 5.4L V8 as the standard engine, with a 6.2L V8 becoming the optional engine; along with flex-fuel capability, both engines were offered with options for conversion to CNG or LPG/propane. For its 2021 model year revision, the E-Series adopts the