It also depends on the model. On ours the sink is very close to the toilet so it makes sense to take them both to the same tank and takes up less room in the basement. Our washer drains into the gray tank. We are an early 2005 model - manufacture date is like July 2004.
Happy trails.........................
Sue and Ed Rowe
Hemet California
2005 3400RL
2006 GMC 3500 Dually, D/A, Crew Cab, Long Bed
