The 79261 fits the 200-Series tractors with vertical engine crankshaft and pto on the bottom.
The 520 needs a model similar to 06-42ST07 which was basically the same from 1973-2007. There is also a 2-stage 44" model like 06-44SC01.
The single stage models use a tube and flag to connect the thrower to the vertical arm on the lift. As the lift goes up, the vertical arm goes forward forcing the snowthrower to pivot on the front quick hitch that effectively lifts it.
View them herehttps://lookup3.toro.com/partdex/index.cfm?xCaller=Toro