A delivery device and methods for deploying an endovascular prosthesis within the common and internal iliac arteries are described. The device comprises a pusher catheter (10) having a proximal end and a pusher extension (18) extending proximally therefrom. A tubular prosthesis having a side branch is releasably coupled to the pusher extension (18). An extension dilator (38) extends proximally from the proximal end of the pusher catheter (10), extends at least partially along an external surface of the main tubular body, into a distal end of the side branch and exits a proximal end of the tubular prosthesis. The extension dilator (38) can be tracked over a guide wire which serves to both position the device within a vessel and also to facilitate cannulation of an internal iliac artery.
