Snap and twist in place the "upper distributor basket" to the under side of the new valve
Performa ( 263 and 268 ) only works if you file off two of the notches of the 4 on the Top distributor ( MD1203 ).
The Autotrol Performa only uses 2 of the 4 possible slots and has "stops" that get in the way of the "twist and lock" unless Distributor is modified slightly.
This only applies to the GRAY version of the MD1203, as it turns counter-clockwise to lock in place, which hit the stops on the Performa Valve. And the Performa is the only valve that has this "issue".
There is a "tan" or "beige" version that twists clockwise, and installs on the Performa without modifications.

Also note, that the Top Distributor is Optional on water softener tanks 44 inches and taller ( unless Tannin Resin added, or Resin level above manufacturer's recommend height ).
A normal water softener will have 16 - 18 inches of empty space ( called "freeboard" ) in which to expand during the Backwash cycle.
Top Distributors are REQUIRED if using Tannin Resins in the softener tank, or if Carbon is in the tank ( mixed with Resin or as the primary media in the tank ).
Performa ( 263 and 268 ) only works if you file off two of the notches of the 4 on the Top distributor ( MD1203 ).
The Autotrol Performa only uses 2 of the 4 possible slots and has "stops" that get in the way of the "twist and lock" unless Distributor is modified slightly.

This only applies to the GRAY version of the MD1203, as it turns counter-clockwise to lock in place, which hit the stops on the Performa Valve. And the Performa is the only valve that has this "issue".
There is a "tan" or "beige" version that twists clockwise, and installs on the Performa without modifications.

Also note, that the Top Distributor is Optional on water softener tanks 44 inches and taller ( unless Tannin Resin added, or Resin level above manufacturer's recommend height ).
A normal water softener will have 16 - 18 inches of empty space ( called "freeboard" ) in which to expand during the Backwash cycle.
Top Distributors are REQUIRED if using Tannin Resins in the softener tank, or if Carbon is in the tank ( mixed with Resin or as the primary media in the tank ).