I'm sure this has been talked about at nauseum but I happened to come across the video and I remembered him saying this years ago so I thought I would post the video. If the guy who built the guitars doesn't know then who does?
Since I own two poplar 1983 Kramers, a Northern Ash Franky, owned multiple Maple bodied 1983 Kramers and a 2001 EBMM basswood/maple capped Axis I would very much agree with Mr. Unkert that most likely wood would be poplar since Kramer used alot of poplar in their production.
The warmth of the poplar is a nice offsett to the thinness of the floyd rose.
Could some have been basswood as some have claimed?.... anything is possible.