As I believe Tominco pointed out, a standard Foster quick disconnect fitting will fit into the hole where the Impact's male fitting is located, but extraction is complicated because there isn't enough edge of a Foster fitting showing to grab with your fingertips. If you do want to use a standard Foster fitting, I've found a perfect tool for fitting extraction without scratching the bottom of your rifle. A Bionic Wrench

will slip over the hose and fitting and grab the small exposed edge of the Foster release with ease. $20 at Lowes.
http://www.lowes.com/pd_527-59563-BW8-01R-01_0__?productId=999926694&store_code=1907&cm_mmc=SCE_PLA-_-ToolsAndHardware-_-PliersAndWrenches-_-999926694:LoggerHead_Tools&CAWELAID=&kpid=999926694&CAWELAID=320011480006431864&k_clickID=00061fc8-e978-ff88-c311-000047a153a3

will slip over the hose and fitting and grab the small exposed edge of the Foster release with ease. $20 at Lowes.
http://www.lowes.com/pd_527-59563-BW8-01R-01_0__?productId=999926694&store_code=1907&cm_mmc=SCE_PLA-_-ToolsAndHardware-_-PliersAndWrenches-_-999926694:LoggerHead_Tools&CAWELAID=&kpid=999926694&CAWELAID=320011480006431864&k_clickID=00061fc8-e978-ff88-c311-000047a153a3