An end member assembly dimensioned for securement to an end of an associated flexible spring member for forming an associated gas spring assembly, said end member assembly comprising: an end member body having a longitudinal axis and extending between a first end and a second end spaced longitudinally from said first end, said end member body including a base section and a cap section that are secured together at a single flowed-material joint, said base section and said cap section together at least partially defining a reservoir chamber within said end member body; said base section including a base section wall formed from a polymeric material, said base section wall including an end wall portion oriented transverse to said longitudinal axis and disposed toward said second end of said end member body, an outer side wall portion extending from an outer distal edge facing toward said first end of said end member body in a longitudinal direction toward said second end of said end member body, and an inner side wall portion extending longitudinally from along said end wall portion toward an inner distal edge facing toward said first end of said end member body; said cap section disposed toward said first end of said end member body relative to said base section, said cap section including a cap section wall formed from a polymeric material, said cap section wall including an end wall portion oriented transverse to said longitudinal axis, an outer side wall portion extending from an outer distal edge facing said second end of said end member body in a longitudinal direction toward said end wall portion, and a mounting wall portion disposed radially inward of said outer side wall portion and extending from said end wall portion in a longitudinal direction opposite said outer side wall portion and dimensioned to receivingly engage the end of the associated flexible wall; said base section and said cap section positioned relative to one another such that said single flowed-material joint is formed between said outer distal edge of said outer side wall portion of said base section wall and said outer distal edge of said outer side wall portion of said cap section wall with said end wall portion of said cap section wall detachably supported on said inner distal edge of said inner side wall portion of said base section wall characterized in that said end member assembly further comprises at least one connector fitting at least partially embedded within said end member body. an end member body having a longitudinal axis and extending between a first end and a second end spaced longitudinally from said first end, said end member body including a base section and a cap section that are secured together at a single flowed-material joint, said base section and said cap section together at least partially defining a reservoir chamber within said end member body; said base section including a base section wall formed from a polymeric material, said base section wall including an end wall portion oriented transverse to said longitudinal axis and disposed toward said second end of said end member body, an outer side wall portion extending from an outer distal edge facing toward said first end of said end member body in a longitudinal direction toward said second end of said end member body, and an inner side wall portion extending longitudinally from along said end wall portion toward an inner distal edge facing toward said first end of said end member body; said cap section disposed toward said first end of said end member body relative to said base section, said cap section including a cap section wall formed from a polymeric material, said cap section wall including an end wall portion oriented transverse to said longitudinal axis, an outer side wall portion extending from an outer distal edge facing said second end of said end member body in a longitudinal direction toward said end wall portion, and a mounting wall portion disposed radially inward of said outer side wall portion and extending from said end wall portion in a longitudinal direction opposite said outer side wall portion and dimensioned to receivingly engage the end of the associated flexible wall; said base section and said cap section positioned relative to one another such that said single flowed-material joint is formed between said outer distal edge of said outer side wall portion of said base section wall and said outer distal edge of said outer side wall portion of said cap section wall with said end wall portion of said cap section wall detachably supported on said inner distal edge of said inner side wall portion of said base section wall characterized in that said end member assembly further comprises at least one connector fitting at least partially embedded within said end member body.