anybody from med tech major or chem major could give us an explaination?

anyway, i've done the most part of draining the coolant but there's only 8/10 of a gallon of coolant drained out as it should be around 1.5 gallons....there's another drain plug on the transaxle on the right side which is shown in the owner's manaul that i couldn't find it under the car. any idea about this? my accord is a ex-v6. thanks a lot!