typically the reason for missing parts, is people not giving what they were supposed to on used head units, or people giving too much stuff away.
What exactly are they supposed to give with the head units? I just removed mine and the new head unit came with new mounting hardware and o-rings. I wouldn't expect to send my used/old o-rings or bolts with the blower.
Ill be ordering a parts box from you guys very soon and am also hunting for a clean head unit. What should I look out for when purchasing the head unit, i.e what parts SHOULD it come with it?
The head unit and the 'roval' TB at the very least. Depending on which kit you get and how you are having the cal or tune done you will also need injectors. Something else I recommend if you want the Whipple cal is to specify that you are going to run their cal so that you get the closed air box, (the open one is junk) the correct TB to MAF pipe and the harnesses for ACT2 and HE pump control.
I just bought a Gen 3 for my car. The new blower came with the head unit, new gaskets for the fittings, new bolts to secure it to lower manifold, blower to lower manifold gaskets and TB gasket. It also came with new supercharger oil.