Wheel Horse transmissions fall into two main categories:
	The geared transmissions either being designed and manufactured 
			by Wheel Horse or Peerless.
	Hydrostatic transmissions manufactured by either Sundstrand or 
			Eaton.
		
		
			Wheel Horse
			Available as a 3 speed+reverse on early models.
			Later marketed as a 6 speed or even 8 speed with 
			the addition of a high/low transfer box.
			Peerless
			Typically 3 speed+reverse apart from some 6 speed 
			models fitted to B series tractors. These were also the transmission 
			used on vertical shart engine models.
			Sundstrand
			Early hydros used on charger, GT14 were hydrogear/piston. 
			Later placed by piston-piston types - approx 1973 onwards.
			more info here
			Eaton
			Used on many hydro models from 1976 onwards