<P> Both HSV vehicles were built in two series, the 2003 "Y Series II" (the wagon was actually available as of October / November 2003) and an updated version of the "Y Series II", which included some of the upgrades found in the newer "Z Series" HSV models . These later models are quite rare, with a build life of nine months from April 2005 to December 2005 . </P> <P> As with the related Holden VY all - wheel drive vehicles, the HSV Y Series AWD vehicles as built from September 2004 to March 2005 confusingly have Z Series compliance and Vehicle Identification Numbers; this correlates to the building of new specification Holden VZ and Z Series HSV non-AWD cars during this period . </P> <P> The updated Avalanches with some of the Z Series upgrades can be externally visually differentiated from the Y Series versions by their re-profiled front bumper unit that looks less aggressive and which features a more integrated appearance to the auxiliary driving lights . </P> <P> The Avalanche vehicles were fitted exclusively with the 5.7 - litre LS1 V8 engine rated at 270 kilowatts (360 hp) of power and 475 newton metres (350 lb ⋅ ft) of torque, mated to a four - speed 4L65 - E automatic gearbox . Permanent all - wheel drive was calibrated to deliver 62 percent of the power to the rear wheels, thereby maintaining a rear wheel drive feel to the handling of these vehicles . </P>

2004 holden commodore vy ii 25th anniversary review