I am finishing up a rebuild of my 455 and am kinda embarrassed to say that I don't know what this is...and where it goes. Some kinda PCV and on the valve cover? And what does thr little port connect to/operate?

 

That is a vacuum modulator for an automatic transmission, but it is bent / broken.

 

Great. Thank you.

 

Unfortunately that style is no longer available. Standard was making that style up until about 10 years ago. They were gold however but you can paint them black. The current ones they sell is the tiny gold one that doesn’t look at fir properly,

 

So the new ones on Amazon, etc. don't fit? Or is it just that they don't look the same?

 

Autozone MV 100. It’s a much smaller modulator, and is adjustable to fine tune shift points. About 20 bucks last time I bought one.