I understand this post is about a year old, but I just started looking.
These are tough to find and just as hard to find a picture of one.
In case others are wondering what the deal is, this arm is a very long 12" compared to a standard 289 fork. Almost 3" longer. It's only used on 67 HiPos and 67 through early 68 390 4Vs (only, not 2V). That's why they are rare.
In the pic below I'm using the small T.O. bearing version of the 12" fork found in a late 60s 390 F150 and it's pictured next the 9" version everyone tends to use as a replacement and fitted to my car.
This is a length comparison. The F150 version is not correct except for length.
I'm still looking for the correct picture of the 67 fork. And the real thing for use in my car.