Funny as to what additional stuff you can find once you enable the Extras menu and actually download something from it--for grins I took a look at the com.garmin.onboard.com.Usa.plist...lo and behold, it listed the actual filename of the terrain file (aka, Panorama View 3D)--it's gmapdem.img. Thanks to those folks who provided links to download it--I was able to install it and voila:

[Only registered and activated users can see links. ]

[Only registered and activated users can see links. ]