Hi! My first post (Question) I have a 1987 D100 with a slant six. I want to know why there is three lines on the fuel filter? I thought that any return line to the tank would come off of the carb.

Hi! My first post (Question) I have a 1987 D100 with a slant six. I want to know why there is three lines on the fuel filter? I thought that any return line to the tank would come off of the carb.