Well the frame is part way through Mark 3 production at least, as it has the revised rear subframe design with mounting below the level of the swingarm and not above (see seventh image.) Chainguard attached to the swingarm (T35 had it attached to the subframe), and the swingarm still has the mounts for the pillion footpegs (Mark 4 onward had them on the toolboxes.) So a frame midway through 1948 production. The engine is T35 (Mark 1) or at least the cylinders and heads are. Anyone inquring should get the frame and engine codes to get a possitive dating. It could be a factory replacment frame, they were replacing them under warrenty as frame fractures were a problem. So not necessarily a bitza, but caution required.
-Doug