You have a Trademaster. The Taskmaster was standard on 5000 series (LCF) trucks, optional on 6000 series w/2bbl, standard on 7000 and 8000 with 4bbl. The Workmaster (348) was only used on the 9000 and 10000 trucks. There was also 1 more V8 engine used in those trucks, I don't think it's mentioned in the '59 supplimant as it was pretty much phased out by then, and that one was the Loadmaster 322. That one was used in 7000-10000 series trucks, starting in '56. It was standard equipment on the Tandem Axle equipped trucks.

Bill Burmeister