TMG,
My understanding was that JD had more than one F-612 (2, I think, but not sure), and had substantially modified one of them over time. To my knowledge, all -612s were solid, flat-backed, 18" jumbo rosewoods. In the late '60s, Hoboken experimented with a veneer rosewood which was used in archback configuration on some F-50R and F-412 SPEC models (I have one of these F-50Rs from 1967, and Hans has a picture of one of the F-412 SPECs). That said, one person I spoke to remembers some laminated rosewoods from the '70s, so I can't state that -612s were definitely all solid rosewood, but I do think so.
