Our mounting base is the same for the Fortrex and Ulterra, but the sliding metal brackets are only directly compatible with the Ulterra. The Fortrex can be used with the metal brackets, but we have an adapter plate: TMA-1 to accommodate those scissor style motors.
You would need 1 base mount (probably the SS-7-HD), 2 set of sliding metal brackets and one TMA-1 adapter plate. In order to remove the trolling motor off the mount, you unscrew the 2 wing screws (inboard side) and slide the motor off the mount, horizontally, into the boat.
TMA-1:
https://shuttleslide.com/product/tma-1/SS-7-HD:
https://shuttleslide.com/product/ss-7-hd/If you are interested, give us a call and we will add the extra pair of sliding metal brackets to your order because we do not sell them separately. I attached a picture of the Fortrex attached to our SS-7-HD (sitting on top of the TMA-1 plate).