HI guys

I'm trying to install new fuel lines on my 1995 Chevy 2500 6.5L diesel turbo, I've come across this hold down connector on the top right of the engine just in front of the firewall but I can't seem to figure out how to loosen it up to be able to get the old lines out, there looks to be a bolt with nut on it just below this but I"m not sure if thats what I need to loosen to open this up or not, there are wire harnesses in the way or I'd take a picture to show what I'm talking about. anyone have ideas on this?