Chevrolet: 91 Grand Am Brake Lines, thread number, autozone

Question
I'm trying to replace the brake lines on my wife's 91 Grand Am. The brake lines I bought will not thread into the master cylinder and the "adapter" I was sold by Autozone was for a Ford and it doesn't seem to thread in very smooth. Can you tell me if my original lines are metric? I've seen adapters on websites that convert to #3AN or #4AN but I don't know what it means. ANY help or direction would be appreciated!
Thanks.

Answer
Hi Larry, yes they are metric, no you cannot get the lines with the proper nuts on them unless you go to the dealer. You have two options, take the old nut to the parts store and see if they can match it, or cut the new line a few inches back from the end and use the original nut and use a joiner to put it back together. I cannot remember what thread number the adapter is off the top of my head, I usually take the tray of adapters to the vechicle and match it that way(I know its different when you work at the dealer than when your a do it yourselfer) so good luck Larry. I hope this helps you if you need more info just let me know. Regards, Keith.