There's no way for sure to know the age if there's no date code stamped into the lid vent. The diamond pattern on the door is an indication of an older door, they haven't done that for a long time, but I don't know of any way to definitively age this grill. You mentioned via PM to me that the door and legs are aluminum because a magnet doesn't "stick", so it's not the earliest 1981 version. But it may be from the 80's after they switched to aluminum door and legs or maybe early 90s. The lack of date code stamp is curious and unfortunate.