oil gauge line

[flaa1a]

I am taking off the cluster and have read a few threads on how to do it. Pretty self explanatory. I am having a problem disconnecting the oil gauge line. I see where it goes on the back of the gauge, but I am trying to use a wrench and seem to be chewing up that nut pretty bad. Can anyone tell me the correct size of that nut that connects the line to the back of the gauge?

And I looked in the FAQ and saw a couple of discussions about gauge rebuild or refresh threads, but couldn't find one!

Anyone have a link?

Randy