The 7.3L Power Stroke was introduced in 1999 and continued through mid-2003, produced by International Navistar. This model was also known as the “Super Duty” body style. The 99-03 7.3L Power Stroke is an electronically controlled direct injection which uses a split shot HEUI (hydraulic/electronic unit Injector) fuel injector backed with a high pressure oil pump (HPOP). The 7.3 utilizes the HPOP in conjunction with a low pressure lift pump to create an overall fuel pressure of 21,000psi. The HEUI injectors were used to improve performance, lower overall emissions, and increase fuel economy. Ford introduced the intercooler in 1999 to cool the charged air and increase the air density which would increase the horsepower potential. The 7.3L continued to use the Garrett single turbocharger and upgraded it to the GTP38. These 99-03 7.3L Super Duty’s had the option of a ZF S6-650 6-speed manual transmission or the Ford 4R110 4-Speed automatic transmission. The 4R110 was an upgrade from its predecessor E4OD.