Not going to add the assembly plant to the title this time since I think its going to be difficult to find examples from any 68 with a T code.In the pictures I have from all three plants very few pictures are of the passenger side of the engine compartment and most of the time the angle has the air cleaner snorkel and/or the S tube right in the way
of these section of the shock tower. If we get so many responses and examples we can slit the topic later. One 68 NJ T code example
Did find an unrestored T code from NJ that did not have the retainer where yours or the car below is/was. Did look through all my San Jose and the ones where I could see the PS shock tower none have anything secured or attached there either. You mentioned the assembly manual but of course those include mistakes or parts and practices they didn't use. If I might ask what is the date of that page and the noted revisions?
Not sure if you looked in the Unrestored Picture section under the title
Topic: 68 T code Dearborn - Unrestored Picture Thread The fourth picture below the area of "Engine Pictures" is a particle view.
Here is that picture from that Dearborn example
Would not expect to find originals/NOS or reproduction but someone else may have traveled down this path before.
BTW and in hopes that it will help make your car closer to how it was originally built your bolts and nuts that hole the spring covers in your front wheel wells to the shock tower were not originally painted black but were P&O
