A modular endovascular graft assembly, comprising: a bifurcated main graft member formed from a supple graft material having a main fluid flow lumen therein, an ipsilateral leg with an ipsilateral fluid flow lumen in communication with the main fluid flow lumen, a contralateral leg with a contralateral fluid flow lumen in communication with the main fluid flow lumen and a network of inflatable channels disposed on the main graft member including the ipsilateral and contralateral legs which is configured to accept a hardenable fill material to provide structural rigidity to the main graft member when the network of inflatable channels are in an inflated state and which includes at least one inflatable cuff disposed on a proximal portion of the main graft member configured to seal against an inside surface of a patient's vessel; a proximal anchor member which is disposed at a proximal end of the main graft member and secured to the main graft member, the proximal anchor member including a self-expanding proximal stent portion secured to a self-expanding distal stent portion with struts which are disposed between adjacent crowns of the proximal stent portion and distal stent portion; at least one ipsilateral graft extension having a fluid flow lumen disposed therein with the fluid flow lumen of the graft extension sealed to and in fluid communication with the fluid flow lumen of the ipsilateral leg of the main graft member; and at least one contralateral graft extension having a fluid flow lumen disposed therein with the fluid flow lumen of the graft extension sealed to and in fluid communication with the fluid flow lumen of the contralateral leg of the main graft member characterized in that the cross sectional area of the material of the distal stent portion, the proximal stent portion and each strut remains substantially constant from the proximal stent portion to the distal stent portion adjacent each strut. a bifurcated main graft member formed from a supple graft material having a main fluid flow lumen therein, an ipsilateral leg with an ipsilateral fluid flow lumen in communication with the main fluid flow lumen, a contralateral leg with a contralateral fluid flow lumen in communication with the main fluid flow lumen and a network of inflatable channels disposed on the main graft member including the ipsilateral and contralateral legs which is configured to accept a hardenable fill material to provide structural rigidity to the main graft member when the network of inflatable channels are in an inflated state and which includes at least one inflatable cuff disposed on a proximal portion of the main graft member configured to seal against an inside surface of a patient's vessel; a proximal anchor member which is disposed at a proximal end of the main graft member and secured to the main graft member, the proximal anchor member including a self-expanding proximal stent portion secured to a self-expanding distal stent portion with struts which are disposed between adjacent crowns of the proximal stent portion and distal stent portion; at least one ipsilateral graft extension having a fluid flow lumen disposed therein with the fluid flow lumen of the graft extension sealed to and in fluid communication with the fluid flow lumen of the ipsilateral leg of the main graft member; and at least one contralateral graft extension having a fluid flow lumen disposed therein with the fluid flow lumen of the graft extension sealed to and in fluid communication with the fluid flow lumen of the contralateral leg of the main graft member characterized in that the cross sectional area of the material of the distal stent portion, the proximal stent portion and each strut remains substantially constant from the proximal stent portion to the distal stent portion adjacent each strut.