I am building a large sled 22.5" x 40" for the community shop in AZ.  Got the Rockler aluminum runners and searching the internet found what looks to be the best way to secure them to the sled base.

Here is a link that the two embedded links are valid for and not buggy.
https://www.ncwoodworker.net/forums/index.php?threads/how-to-attach-rockler-aluminum-miter-bars-to-cross-cut-sled.67480/

Basically you double back tape the Rockler runners to the sled bottom.  There is a drill/tap that you go through the aluminum threaded holes in the Rockler runner bars.  The front has a short drill bit and you go through the plywood base, counter bore the top side to fit the 1/4-20 FH screws.

Got the drill/tap bit and 25 of the FH screws for a bit over $18.

Got the base cut to size, push fence laminated and flattened  & rear fence made already.  Rockler runners in hand, wowie.   Tomorrow is sled day, likely the following day or two when I cuss and dial it in.  We leave AZ May 11 and return to the Great PNW (actually rainy PNW).

The sled will not be dead nuts 90 and someone will use a full kerf blade on it before I return in early November.  I will take some pictures and post them here.  But this one should be able to take the wiggle out and re-square when I return.

daveg, SW Washington & AZ