No, no modification is needed to fit in an ETA 7750 or IWC 79320. Only the hands (the holes in the hands) differ: Genuine ETA 7750 all variants (all) Hour 2.00mm Minute 1.20mm Center Seconds 0.25mm Subdials 0.17mm Old Asian 7750 version all variants(21,600 BPH) Hour 2.00mm Minute 1.20mm Center Seconds 0.25mm Subdials 0.17mm New Asian 7750 (28,800 BPH) Normal ones Hour 2.00mm Minute 1.20mm Center Seconds 0.20mm Subdial 0.20mm