I have updated my game to 0.6E but the server I race on every week is still on 0.6B. Hopefully it will be updated before the race tomorrow, but is there any way for me to re-install 0.6B in case it is not? I can't find installers for 0.6B anywhere.

You can download it from here: http://www.ausgamers.com/files/details/html/59304

Thanks heaps for that. I've been really looking forward to this race

rename your current LFS.EXE to LFS6b.exe or alternatively LFS6e.exe when you switch. Rename the version you want to use to LFS.EXE. No mess.