Curtis George, Royal Oak Mi.

The legacy has six rails but really only needs two to run the carriage.  I bought some uni-strut
Model P3301 that is a dead ringer for the Legacy rail system.  Only the uni-strut dose not have the small channel.  What I did was replace the two inside rails and the bottom rails with uni-strut and added the old rails to the upper and outer edge. That is the outside rails of the machine.  You will need to make some brackets, I used four 1/8"x1.5"x 12" flat stock and drilled  8 holes.  After drilling I wielded nuts over the holes so machine screws could run through them.  I then made four 12"x 1/4" brackets to fit inside the aluminum rail.  Then I made 4 more brackets to fit the underside of the outer rail 1.5x 3" flat stock.  I drilled two holes, and secured them using legacy's mounting brackets and screws.

NOTE the brackets go on the bottom and inside on the aluminum rails.  The rails the carriage rides on.  Now the assembly, connect the bottom brackets on Legacy, remaining outside rails, then slide in the small flat stock and brackets (with nuts wielded facing inside) screw down bracket to inner side of the rails. I needed to connect two set to make the 15' I needed. (each rail is 5' long).  You can make new support brackets or use Legacy's old support brackets (that's what I did) I made my Legacy 15 feet long to complete a job( which I needed 14 feet).   Latter I rebuilt my legacy back to 60"  ("Well I needed to just keep some extra length.)  Mine was originally 48") The only problem with this increasing of size was the drive rod needs to be either disconnected or a new rod must be gotten. ( I disconnected it) because it wasn't needed for the job I was doing. I made stop blocks and used them the stop the travel where necessary. My kids turned the wood and I controlled the carriage and router. IT WORKED WELL for that job. but keeping an 8 year olds attaché is rather difficult.  " KEEP IT TURNING!"  " DAD IM TIRED!"  "Just keep it going we are
almost done!" 

looked up Uni-strut of the internet, the headquarters is.

      Unistrut Headquarters
      35660 Clinton Street, Wayne, MI 48184
      Tel: 800 521-7730, Fax: 734-721-4106
                  Unistrut Illinois
                  1140 W. Thorndale Ave.
                  Itasca, IL 60143
                  Contact: Sue Dial, Rosie Grasso
                  Phone: 630-787-6062, 630-787-6057
                  Fax: 800-742-0223
                  Website: http://www.unistrutconstruction.com

                  I believe they can help you.  p3301  (1- 5/8"x 1 -3/4") I
believe it was 12 gauge. page 34 in there catalog.