The nuts that are afixing the hardware to the drawers are one piece right? These are dateable* but for the life of me I can't find where I read this... I'll keep searching (altho I tend to get distracted) but at one point in time things changed and hardware was afixed with 2 separate pieces, one being a square nut.
This may help and like I said, I'll keep searching where I read that. May or may not help
* Disclaimer: Not sure "dateable" is a word but you get my drift