I would go to my local Ace hardware... or that type place...and tell them what happened and ask for help.... typically you get one each of some close and take them out to the car and try them...and then bring the others back and put them into the CORRECT box... so as to not mess up someone elses day who sent the wife to pick up some specific size and she did not check to see what was in the ' 3/8ths ' box.... LOL
Most people , even if they have the same as yours... are not going to know the pitch for a metric thread ....