What is this? Vacuum box on 70 mach 1

[callys]

The painless harness has no provision for it...

Some kind of vacuum box?

Found it below....

 

[ForceFed70]

Wow. Not sure WTF that is. It's defiantely not a part that I have in my Grande.

Do you have any vacum operated accessories? Only things I can think of are AC or Cruise Control.

 

[callys]

Apparently it is an old emissions system for controlling distributor advance based on speed

1970 Speedometer question/challenge - Vintage Mustang Forums

It is not mentioned in the manuals I have

I only found it because you mentioned cruise control, and so I searched that and apparently other people have thought that to be its purpose as well