gurgling gas tank

[73goldduster]

i have a question for you guys about this wierd gurgling sound coming from my gas tank lately. it sounds like when you turn a bottle of water upside down and air tries to push in, chugging or gurgling sounds. this car is a bone stock slant 6 with the 1 barrel carb. i really dont know very much about these cars, could it be a blocked fuel return line? where do i look/ how do i check? is this even anything to worry about?
thanks for the help!