Nissan only started keeping key codes on file in mid 94 for 95 models (and some 94 models) and it did not have to be recorded by the selling dealer, NNA kept these on file with the VIN. You should have a sticker somewhere around your glovebox with an X and four numbers after that (ex: X1234). They do stick on the box pretty well, so it SHOULD be there, and they were randomly put on so could be anywhere under there. You can also try the door lock cylinders for numbers and if you did have to pull something out, I would get the passenger side lock since it is going to be the least worn down out of the cylinders.