That's an extremely efficient design to have the heat sink and logic board come out in one piece so you don't have to reapply thermal paste every time. Speaking of, looks like apple really cleaned up their act and applied a correct amount of thermal paste this time around. If it were in old 2,2 MacBook Pro you would be seeing the over applied thermal paste spilling over. Do you have photos of the CPU and GPU before you cleaned the paste off?
Is this UJ898 standard 12.7mm height?
Apple must of got first dibs on this new drive, I only see UJ-875A and UJ-880A on the Panasonic Industrial website.