Hello friends, I've been wondering where you would normally see 86 foot boxcars in service. Also would they be in unit trains, mixed freights, or some other type of train?
Mixed freights, most likely. A unit train of 86 foot boxcars would be rather impracticable. They were usually often used to haul auto parts, so any railway serving the auto industry could have them, but just like any other boxcars, you could ultimately put anything inside them and move it.
The big boxcars you mention were usually used in auto industry service. The loads they carry "cube out" before they become overweight for the car's rating. In rail transportation's heyday, good sized trains of these parts cars (plus flats stacked with auto frames, 50' boxcars with heavy engines, transmissions and axles, 60' cars with more misc parts, and autorack with set up autos were sent from Detroit for the assembly plants and auto markets on the west coast. One such train was the Ford FAST; Ford Auto Service Train. It was a ultra-high priority short fast freight from DT&I's Flat Rock Yard in Detroit. It carried Ford parts and set up autos to California's Milpitas Ford plant and the CA market. D&RGW carried it over the Moffat mainline when received in Denver from Rock Island, and later after Rock lost the Ford contract, to Mopac at Pueblo and over Tennessee Pass. The trains were handed over to WP or SP at SLC/Ogden. The train alternated an all-UP routing from its eastern connections with the Rock/D&RGW/WP (MP/D&RGW/SP) periodically. When the Ford plant in Milpitas closed in 1982, this train changed to carry set up autos in both directions and parts for CA suppliers.
I take it the boxcars aren't as popular now. N&W and Southern both had these cars and Conrail as well so I think NS must have a good sized fleet of them operating up North.
Washington Central had some "Maxi-Cube" 85-ft boxcars in the WCRC 8xxx series that I believe were used for hauling toilet paper. http://rrpicturearchives.net/showPicture.aspx?id=2399501