What is the gear oil capacity of freightliner rear?

Freightliner makes trucks in the Class 5 - Class 8 range. You would need a make an model in order to answer this. At the back of the pumpkin, there'll be a fill plug... unbolt it (you can use a 5/8" wrench or 5/8" 8 point socket to do this), stick your finger inside.. the oil level should come to the bottom of that hole for the fill plug. Anything less, and you need to add oil. Anything more, and you need to let it drain.