The Marx Sinclair tanker was a refresh of the earlier and more common Marx 553 Middle States Oil tanker, a design that originated way back in 1935. The Sinclair tanker made the old design book newer, and perhaps more relevant for its era. It came in two major variants, one much easier to find than the other. It dates to 1956 and 1957.
David Farquhar is a computer security professional, entrepreneur, and author. He has written professionally about computers since 1991, so he was writing about retro computers when they were still new. He has been working in IT professionally since 1994 and has specialized in vulnerability management since 2013. He holds Security+ and CISSP certifications. Today he blogs five times a week, mostly about retro computers and retro gaming covering the time period from 1975 to 2000.