Hi Henk,
There is a voice named 'It60'sOrgan' in the 'Organ' category of the 'GM2' Preset voices. I don't know if this is anything like what you are searching for!

The 'GM2' voices do not have a dedicated panel button to access them. Instead, you access them by first opening the Voice selection screen 'Preset' tab.
If the 'UP' icon at the bottom right of the screen is lit, press the upper #8 button ('UP') enough times until it goes out. You are now at the top level of the Voice folders, which is where all the voice category folders are located.
Select page 2 ('P2') if necessary and you should see the 'GM2' folder listed. Select it and it will open to show all the category folders within it (I suspect that it will be on 'P1' page).
Open it to list the voices within it.
At this top folder level you will also see another voice category, 'GM & XG', which like 'GM2' doesn't have a dedicated panel button. It is worth looking in there as well to see if there is anything like the voice that you want.
Remember that you can edit the voice a little using the 'Sound Creator' as described starting on page 95 in the 'PSR-3000 Owner's Manual'. This is the only way to change voices on the 3000. Although you can load edited voices made by other people, they will simply be modifications of the Sound Creator parameters. After making any changes remember to save the edited voice as a 'User' voice in the 'USER' area, USB or Card.
Regards
Ian