Leo - It was free, but I didn't grab it when I had the chance. I was pretty much thinking along your lines. As a second thought I thought it might be worth the effort if all I needed to do was remove the main shaft bolts, remove, then drop the 650 shaft into the Grabber.
The other option I considered was just sending it back to MEC for an overhaul, but I don't know how much MEC charges for that.
And I have trash cans full of resized once-fires for the 650. And I probably missed my chance to get it. Maybe I ought to call MEC to see what the charge for an overhaul.