Xcode 2.3 Release was released on 23 May 2006 and requires macOS 10.4+.
It can be downloaded from https://download.developer.apple.com/Developer_Tools/xcode_2.3/xcode_2.3_8m1780_oz693620813.dmg.
Release notes are located at https://download.developer.apple.com/Developer_Tools/xcode_2.3/xcode_2.3_readme_20060522.pdf.