1965 Barracuda speedometer confusion

My understanding is that '66 went to a more generic version which costs only $15 as opposed to the $130+ I'll have to spend. If you see the image above you'll notice the whole housing with the gear on there as one piece. No way to separate from what I can tell. So well done buying a '66 instead of the '65;)
I see. Thanks for the teaching. Can you pull the core out? Worth a try.