1965 Barracuda speedometer confusion

What is the difference in the end (s)? Just one end and if so which? Is yours smaller or does it attach differently? I lucked out and got one for my 66 (I know) from Napa. I should order a extra if they discontinue them. LOL

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;)