Sorry to say I can't answer that definitively Terry. I think the early rods (with the loose reel seats) had a different blank than the later green/grey rods with the screw seat, but after that I'm not too sure.
But even if every different iteration DID use a different blank, they're all good - I've got one of each from the early 50/50 duplon-cork version to the most recent Rovex version, and they've all proven themselves several times over.
In fact, I think the only one I haven't got is the prototype version with a full foam handle that, from memory, was branded Ryobi (as opposed to Ryobi Masterline) and sold exclusively at John's shop.