You sure it's a Big Un? (Massive Flanges) the early ones had quite thick centre sections and the later ones were skinnier (still had huge flanges)
The Bulb's had a screw together adaptor, that's why I ask ( also big Un's are only 5 bolt which screw directly to the body and don't use a separate spider...
my early Big Un's had a normal QR set up which I removed and replaced with a central sleeve and wider bearings which the spacers sit over
My later Big Un (now sold) had a spacer tube, the bearings and caps which popped into these. This one may have had a screw together QR set up but Im not sure...
