You check the Expansion Bay of your PS2 and see if there is a screw in the
Expansion Bay. If there is a screw in the Expansion Bay similar to the one indicated
by the Red Arrow in the following picture, then your PS2 is Version 5 or
Version 6. Otherwise, it Version 4.
To further identify whether you have a Version 5 or Version 6 PS2,
you have to open up your PS2 and check the main board of your PS2.
The difference between Version 5 and Version 6 PS2 30001R model is shown in
the following image.
