I really liked the trim idea on this truck, so I searched to find more info on it. Here's the article about it: http://www.customclassictrucks.com/featuredvehicles/0606cct_1962_chevy_pickup_shortbed/
Alternate Trim I like how he used trim across the back of the cab, tying together the Custom Cab Sail Panels.
That was the first thing I spotted too. Like you said it really ties everything together. It's a shame that set isn't reproduced.
I had forgot to post here that this thread inspired me to make my own trim for the back of my truck... basically modified some used bed side trim.