Originally Posted by bowtietim
Looks like the collar is different to me,you might check that.

I think your onto something. The '54 manual shows the curved collar like I have:
http://chevy.oldcarmanualproject.com/shop/1954truck/54ctsm0619.html

But, this thread says that the '54 manual shows the car, not truck vacuum advance

So I have a new truck vacuum advance, but the collar from a car 235.