Hum - that is a tough question to answer... ok

The UAW contract for the GTO was as followed..

3 year with 18,000 max units sold the first year. I think only about 12,000 where actually made.
In 2007 the new body will be release (Zeta) still designed by the aussie but will be brought over to the USA for builds i.e. New Camaro, Chevelle, GTO (USA). So in actuallity the Holden GTO will only be produced 04-05-06 then in 07 there will be a new release of vehicles.
This of course is all pending to change but that is the latest news from GM.

Now the 05 is a LS2 GTO (6.0L) same motor that is in the C6 Vette. The changes to the 05 are as follows
Hood scoops (non functional)
Dual EXIT exhaust w/ 3.5" tips on each side
Upgraded brakes with red painted cal and say GTO
Purple and Barbados blue delete and 2 colors added.
If you want a collector 04 GTO get the Pulse Red, only the last 800 made where availible for order in pulse red. Changes in Pulse Red (option W40)
Silver Guage cluster (instead of red)
Red Embroidered GTO on seat (not silver)
Pulse Red exterior color (Darker than Torrid Red but not metallic)
Only 800 possible made. Of 12000 cars that is about 6%.