I have to comment about Flint based on what I have seen in engine assembly over the last 30 years or so - I can count among my customers GM Spring Hill (formerly Saturn) for 1.9L, 2.2L, and 2.4L- 4's and transmissions, Nissan Decherd for V6 and ZH2 5.6L V8 production, Navistar/International diesel production V8 (5 heavy transfer lines), Hyundai Montgomery Theta 4 and V6 lines, and got to tour GM Opel L850 2.4L KS Germany and the plum of Stuttgart, Mercedes Engine V6-V8 production. I have helped tool a lot of processes from camshaft to crank machining to cylinder bore/block machining, plus small parts machining like water pumps/front covers and everything else, but in all this time I have never seen anything to beat seeing the film of the block gang installing pistons on the V8 line in Flint. Mercedes touted their robotic assembly in the Stuttgart plant, but the whole time I observed the place I kept thinking about the pace at which our venerable small blocks sailed out of the Flint plant (since 55?) and into what many of us own yet.
Kudos to all who ever worked in either facility. Your craftsmanship still powers us today -