I noticed the link in the start post isn't working anymore. Since this thread is sticky: here's the current link: Link to the us version of the ekat-site
I also noticed that the partnumbers that John Langevin were looking for aren't included in the US version. But if you go to the Ekat site via a European festool site, you can find those partnumbers.
For example: link to Dutch version of ekat site
To get to the mentioned numbers: select "routing" in the left column; then "routers", then "accessories for routers", then "MFS400/700...", then "extension profile"
(the option in bold is not available via the us ekat). Here you find that the part John was looking for is number 466353
(the number is for all 3 pieces (the threaded insert, the bolt and the sliding nut)
(It is not possible to link to a specific drawing in the ekat site, that's why I wrote out the "route" to get there)