A brand new tank from DAF won't come with the couplings. A leak from the pipe will either be the coupling or the pipe ,without seeing it I don't know..If that is your issue thn you won't need a tank .Drain your tank ,remove the pipe and unscrew coupling ,Fit a new coupling with any O rings or washers ,make sure there are no nicks or damage to the pipe and the end is cut straight,otherwise is will leak ,and push in fully
norb, October 2013