Technically not an assembly "line" photo, more assembly research.
This is a Keller machine -
It is a tracing/duplicating machine; the pattern is located at the top, and the bottom portion is machining a die or a mold, in this case.
The pattern is lined with masking tape, to provide roughly .007" additional material, which is then polished out by hand. My Dad, trained as a tool & die maker, called masking tape "Keller tape" in casual conversation for this reason.
You'll note the pattern in this case is the original mold for the front clip of the '53 Corvette. The photo was taken at the GM Assembly Research Center (GMARC), located on the north east corner of the Flint Assembly property, and is also where the first 300 Corvettes were assembled.
I worked in this building off and on early in my career, but sadly this building is no longer there.
K