At the 2004 North American International Auto Show, Ford introduced a completely redesigned Mustang, codenamed \"S-197,\" that was based on an all-new D2C platform for the 2005 model year. Developed under the direction of Chief Engineer Hau Thai-Tang and exterior styling designer Sid Ramnarace,[26] the fifth-generation Mustang\'s styling echoes the fastback Mustangs of the late 1960s. Ford\'s senior vice president of design, J Mays, called it \"retro-futurism.\" The fifth-generation Mustang is manufactured at the AutoAlliance International plant in Flat Rock, Michigan. The base model is powered by a 210 hp (157 kW) cast-iron block 4.0 L SOHC V6, which replaces the 3.8 L pushrod V6 used previously. The Mustang GT features an aluminum block 4.6 L SOHC 3-valve Modular V8 with variable camshaft timing (VCT) that produces 300 hp (224 kW). The 2005 Mustang GT has an approximate weight to power ratio of 11.5 lb/bhp. The base Mustang comes with a standard Tremec T-5 5-speed manual transmission while Ford\'s own 5R55S 5-speed automatic, a Mustang first, is optional. Though the Mustang GT features the same automatic transmission as the V6 model, the Tremec T-5 manual is substituted with the heavier duty Tremec TR-3650 5-speed manual transmission to better handle the GT\'s extra power.