A grass collection system may have an impeller with a through-shaft that mechanically couples power take off (PTO) energy to the mower deck. The PTO shaft may pass through the impeller and blower housing to power the mower deck, resulting in a compact mechanism. The PTO shaft may pass through a grass tunnel that connects between the blower housing and the mower deck, then may be connected to the mower deck to power the mower blades. The grass collection system may be deployed on a front mounted deck tractor that has front wheel drive. The front wheels may each have a hydrostatic pump and gearbox, and the PTO shaft may pass between or under the front wheel drive systems in connecting to the mower deck.