28 GPM

$16 for 40 GPM hydraulic quick couplers - [1]
Safeway S56-6 - 28 GPM - http://www.safewayhyd.com/s56.htm
Safeway S21F-6http://hydraulics.safewayhyd.com/item/agricultural-quick-couplings-s20-series/s20-male-tip-half-nipple/s21f-6-1
http://www.automation-dfw.com/pdf_pneu/tema02-hydisostdprofile.pdf
3/4" ISO 7241-1 A Hydraulic Hose Quick Disconnect Couplers 600-12-12S - 6600 Series - http://www.automation-dfw.com/pdf_pneu/tema02-hydisostdprofile.pdf - $25 on Ebay - [2]
3/4" ISO 7241-1 B - specs - [3]

Unknown GPM