hello Juan,i am not 100% certain how your lines are set up,the plug on the bottom side should be to drain the tank with,the outlet on the corner should be your fuel pickup,the adapter should be about 1 inch long,with a female thread on one end and a male thread on the other end,they are available at any hardware or car parts store,what i do if i have a need for this type of threads,i find something that will thread on to it and i take that with me to the store,makes it easier as all the threads look alike,you could take the tank with you if you havent put it back in the car yet?the adapter will be normal pipe thread,nothing special or weird about them.all the old cars used them in some capacity or other.did you have the tank cleaned by someone else?,maybe they removed the original part.let us know how you make out. thanks Harvey Bowness