in doing a gas tank swap on my 240z im installing a 260z gas tank just having one small issue does any one know which on the 260z gas tank is the return line due to both of them are the same size but the 240z the return is smaller

I really don't know, but maybe if you have posted in the technical forum you'll get a faster reply.

some technical minded people don't look much into this part, so they might miss your post.

good luck.

Here's a page I made about fixing a gas tank.

http://warbuddies.homestead.com/gastank.html

Some of the pictures at the bottom may be of help. You should be able to remove the filler neck and/or the sending unit and use a flashlight and mirror to sort it out. Try removing the filler plug and blow air through the tubes. You may be able to hear it coming from the end of the tube.

Cheers

Jim

I would think the return line would enter the tank and finish short. If you had some liquid in the tank you should be able to tell which line goes further to the bottom.Perhaps blow in the lines, or suck, whichever takes your fancy, as long as you don't swallow.