Thanks for the picture! I have a great set of disc brakes for your 2019 Grand Design Momentum Toy Hauler. You are going to need a couple of other parts too to convert your trailer over to a disc brake set up.
I recommend the Kodiak Disc Brake Kit - 13" Hub/Rotor - 8 on 6-1/2 - Raw Finish - 7,000 lbs item # K2HR79. This kit will fit your 2019 Grand Design Momentum Toy Hauler's 7,000 lbs axles and 8 on 6-1/2" bolt pattern.
You're going to need an actuator. The HydraStar Vented Marine Electric... view full answer...