A low profile, two lumen dilator is provided for an arteriotomy closure system. The dilator includes a first lumen adapted to receive a guidewire and a second lumen having a proximal segment that defines a blood marking lumen and a distal segment that receives the distal ends of stabilizers in a common pocket. The blood marking lumen and pocket are arranged in tandem. The guidewire lumen may extend the full length of the dilator or may be shortened to provide rapid exchange capability.