OK, I finally got the 3" risers off. It took the full lexicon of English curse words, plus a selection of German and Creole. The pics below show what these "technicians" from the local shop managed; I had to use my pipe wrench to gat the b$%tards moving, no way a 19mm socket/spanner or anything else was gonna fit in that gap, and helpfully they'd also loctited the threads. (Yes, the liquid around them is sweat). OEM mounts shown on the left.
I have a strong suspicion these buffoons also drilled out the yoke to fit the construction-grade bolt, the OEM shafts are very loose, does anybody know what size the riser mounting bolt holes are supposed to be in the yoke?