quick disconnect -an fittings?
https://ls1tech.com/forums/fueling-injection/199854-fittings-stock-rails-these.html
http://www.gmhightechperformance.com/tech/0409htp_snow/
Came across these while searching for a -6 AN o-ring female to -6 AN flare male adapter or -6 AN 0-ring coupling. Still looking. Might have to get a T or Y and block off 1 port.

