MAC:
https://secure-appldnld.apple.com/itunes12/091-33628-20170922-EF8F0FE4-9FEF-11E7-B113-91CF9A97A551/iTunes12.6.3.dmg
WINx86:
https://secure-appldnld.apple.com/itunes12/091-33627-20170922-EF8CB708-9FEF-11E7-8504-92CF9A97A551/iTunesSetup.exe
WIN x64:
https://secure-appldnld.apple.com/itunes12/091-33626-20170922-F51D3530-A003-11E7-8324-03D19A97A551/iTunes64Setup.exe