Have you tried getting in touch with SM? You can call them and give them your chassis model. Do not email them as this approach does not work too well. Call them.
If you don't need the oddball metric CPU heatsink supports, the rest of the parts are relatively normal. The standard standoffs are 6-32 male-female hex standoffs (I don't remember the length, but I can go measure one if necessary).
Unfortunately, if you need the oddball heatsink supports, based on
other experiences here, Supermicro isn't particularly interested in selling the bag of hardware (which apparently doesn't have a Supermicro part number, just a bag labeled "M/B" which comes with the chassis) to people who bought used chassis. If you contact them, I suggest you use the "I'm changing the motherboards in my SCxxx chassis and I didn't save the extra hardware" explanation (which is true) and not get into where you bought the chassis in the first place unless they ask. And "I don't know, somebody else did that way-back-when" is truthful.
