Yea, they do act as eccentrics by placing the through bolt off to one side - that's what moves the arms in or out as they push against those raised areas that capture the eccentrics. I've seen the same set up on late 60's early 70's Mustangs but on the inboard lower control arm mount. I found the e body upper ctl arm hits at about the 10 to 8 o'clock inboard position on an E body.