I'm 90% sure about this but I want to be certain.In the rear engine compartment, there's a reservoir that I believe to be for the transmission. It says,"hydraulic reservoir.Fluid Only. Dextron3 or equ...
IT is the Hydraulic reservoir- Manual also calls for the fluid to be changed. My Freightliner XCS chassis shows 24 month interval. Interval does vary and some power steering/fan systems have a filter in the hydraulic line -also with a change interval...