Twin directories of 5.1-RELEASE:

[DIR]  ftp://ftp.csie.ncu.edu.tw/FreeBSD/releases/ia64/5.1-RELEASE/
[DIR]  ftp://ftp.csie.ncu.edu.tw/FreeBSD/releases/i386/5.1-RELEASE/
[DIR]  ftp://ftp.csie.ncu.edu.tw/FreeBSD/releases/alpha/5.1-RELEASE/
[DIR]  ftp://ftp.csie.ncu.edu.tw/FreeBSD/releases/amd64/5.1-RELEASE/
[DIR]  ftp://ftp.csie.ncu.edu.tw/FreeBSD/releases/pc98/5.1-RELEASE/
[DIR]  ftp://ftp.csie.ncu.edu.tw/FreeBSD/releases/sparc64/5.1-RELEASE/
[DIR]  ftp://194.186.254.27/.3/FreeBSD-Archive/old-releases/ia64/5.1-RELEASE/
[DIR]  ftp://194.67.80.52/.3/FreeBSD-Archive/old-releases/ia64/5.1-RELEASE/
[DIR]  ftp://194.186.254.27/.3/FreeBSD-Archive/old-releases/sparc64/5.1-RELEASE/
[DIR]  ftp://194.67.80.52/.3/FreeBSD-Archive/old-releases/sparc64/5.1-RELEASE/
[DIR]  ftp://194.186.254.27/.3/FreeBSD-Archive/old-releases/amd64/5.1-RELEASE/
[DIR]  ftp://194.67.80.52/.3/FreeBSD-Archive/old-releases/amd64/5.1-RELEASE/
[DIR]  ftp://194.186.254.27/.3/FreeBSD-Archive/old-releases/i386/5.1-RELEASE/
[DIR]  ftp://194.67.80.52/.3/FreeBSD-Archive/old-releases/i386/5.1-RELEASE/
[DIR]  ftp://194.186.254.27/.3/FreeBSD-Archive/old-releases/alpha/5.1-RELEASE/
[DIR]  ftp://194.67.80.52/.3/FreeBSD-Archive/old-releases/alpha/5.1-RELEASE/
[DIR]  ftp://ftp.mtu.ru/.3/FreeBSD-Archive/amd64/5.1-RELEASE/
[DIR]  ftp://ftp.mtu.ru/.3/FreeBSD-Archive/i386/5.1-RELEASE/
[DIR]  ftp://ftp.mtu.ru/.3/FreeBSD-Archive/ia64/5.1-RELEASE/
[DIR]  ftp://ftp.mtu.ru/.3/FreeBSD-Archive/pc98/5.1-RELEASE/
[DIR]  ftp://ftp.mtu.ru/.3/FreeBSD-Archive/sparc64/5.1-RELEASE/
[DIR]  ftp://ftp.cse.buffalo.edu/pub/FreeBSD-Archive/old-releases/amd64/5.1-RELEASE/
[DIR]  ftp://ftp.cse.buffalo.edu/pub/FreeBSD-Archive/old-releases/i386/5.1-RELEASE/
[DIR]  ftp://ftp.cse.buffalo.edu/pub/FreeBSD-Archive/old-releases/ia64/5.1-RELEASE/
[DIR]  ftp://ftp.cse.buffalo.edu/pub/FreeBSD-Archive/old-releases/pc98/5.1-RELEASE/
[DIR]  ftp://ftp.cse.buffalo.edu/pub/FreeBSD-Archive/old-releases/sparc64/5.1-RELEASE/
[DIR]  ftp://ftp.mtu.ru/.3/FreeBSD-Archive/alpha/5.1-RELEASE/
[DIR]  ftp://ftp.cse.buffalo.edu/pub/FreeBSD-Archive/old-releases/alpha/5.1-RELEASE/
[DIR]  ftp://ftp.mtu.ru/.3/FreeBSD-Archive/ia64/ISO-IMAGES/5.1-RELEASE/
[DIR]  ftp://ftp.mtu.ru/.3/FreeBSD-Archive/pc98/ISO-IMAGES/5.1-RELEASE/
[DIR]  ftp://ftp.cse.buffalo.edu/pub/FreeBSD-Archive/old-releases/ia64/ISO-IMAGES/5.1-RELEASE/
[DIR]  ftp://ftp.cse.buffalo.edu/pub/FreeBSD-Archive/old-releases/pc98/ISO-IMAGES/5.1-RELEASE/
[DIR]  ftp://ftp5.jp.freebsd.org/pub/FreeBSD-PC98/dists/5.1-RELEASE/
[DIR]  ftp://ftp.blackcube.org/pub/ftp.csie.che.edu.tw/FreeBSD/releases/sparc64/5.1-RELEASE/
[DIR]  ftp://ftp.umn.ru/FreeBSD/5.1-RELEASE/
[DIR]  ftp://ftp.highway1.com.au/pub/FreeBSD/i368/5.1-RELEASE/
[DIR]  ftp://ftp.sol.net/.0/releases/i386/5.1-RELEASE/
[DIR]  ftp://194.186.254.27/.3/FreeBSD-Archive/old-releases/pc98/5.1-RELEASE/
[DIR]  ftp://194.67.80.52/.3/FreeBSD-Archive/old-releases/pc98/5.1-RELEASE/
[DIR]  ftp://194.186.254.27/.3/FreeBSD-Archive/old-releases/pc98/ISO-IMAGES/5.1-RELEASE/
[DIR]  ftp://194.67.80.52/.3/FreeBSD-Archive/old-releases/pc98/ISO-IMAGES/5.1-RELEASE/
[DIR]  ftp://ftp.thu.edu.tw/FreeBSD/releases/i386/5.1-RELEASE/
[DIR]  ftp://ftp12.freebsd.org/pub/FreeBSD/releases/ia64/5.1-RELEASE/
[DIR]  ftp://ftp12.freebsd.org/pub/FreeBSD/releases/amd64/5.1-RELEASE/
[DIR]  ftp://ftp.kuban.ru/.1/FreeBSD.1/5.1-RELEASE/
[DIR]  ftp://ftp12.freebsd.org/pub/FreeBSD/releases/i386/5.1-RELEASE/
[DIR]  ftp://ftp12.freebsd.org/pub/FreeBSD/releases/sparc64/5.1-RELEASE/
[DIR]  ftp://ftp.csie.ncu.edu.tw/FreeBSD/releases/pc98/ISO-IMAGES/5.1-RELEASE/
[DIR]  ftp://ftp12.freebsd.org/pub/FreeBSD/releases/alpha/5.1-RELEASE/
[DIR]  ftp://ftp12.freebsd.org/pub/FreeBSD/releases/pc98/5.1-RELEASE/