6.2 diesel fuel filter housing

[lotmarker]

Hey guys. I'm attempting to replace my old leaking, air sucking fuel filter housing with an a/m fuel water separator on my 1987 6.2l diesel chevy step van. Problem is there are 3 lines going to my old housing but only 2 on the replacement. Ive figured that the 3rd one is probably the return line but how do I route it? Any help?

 

[just a number]

you could have one of two possible filter setup.

the round filter mounted to the back of the intake:

if so you've got the same setup as the 6.5's. 1st line from the tank(3/8") 2nd one goes to the IP(1/4") and the 3rd line from the bottom is the drain hose(for water) there is a valve on the end of the line.

Square box:

same number of lines and sizes but the drain valve is on the filter housing instead on the drain hose itself. it also has either just a nipple or a short house at the top corner to bleed the air out. it's a common area to get air in.