Caliber used by 3777 : ETA7750 or Sellita SW500?

I always had the impression that the ETA7750 was used for 3777 but a friend who owns the same watch told me that the caliber has been changed to Sellita SW500. Can anyone verify this news?

www.sellita.ch/images/stories/documents/SW500_DOC_FULL_v.13.09.12.pdf

If it indeed switched to SW500, can anyone be kind to advise when?

In the IW3777 the movement is ETA 7750 based, modified by IWC to 79320. Sellita is used in the Portofino Chronograph, which is modified by IWC to 75320 as I understand.

Your friend is wrong. All pilots' models use ETA or have in-house movements.