To remove the exsisting shift rod and replace it with one that has the slot for the curved shifter, it is removed by taking apart the shift rod from the shifter rod universal joint under the rear seat access plate on the tunnel.
Then remove the two 10mm bolts on the oval plate located on the vertical surface of the front of the chassis frame head located to the rear of where the "battery box" is molded in the forward end of the front trunk.
To remove the shift rod, you then reach down through where the shifter mounts and grab the rod with a large pair of pliers working it forward an inch or so at a time and out the frame head oval plate access hole.
....The problem is the speedster's molded battery box is in the way for the rod to travel forward enough to get it out of the chassis tunnel, you would have to remove the battery and bore a 1.5" hole in the front and rear sides of the battery box for the rod to pass through, that still will be difficult as you have to contend with the forward apron below the trunk handle, not impossible but can be a challenge. Be sure to replace the nylon shift rod bushing located just inside and to the rear of the shifter opening.
To feed the replacement slotted cup rod back into the chassis (after putting in the replacement nylon shift rod bushing) tie a piece of wire to it and feed the wire into the chassis tunnel and pull the wire to feed the rod back in until you can again grab it with the pliers push it along through the tunnel and through the shift rod bushing until the slotted rod cup is centered in the shifter opening. Hope this makes sense.