You only NEED to order the motor With Cam Gear... if your current motor gear and Cam GEAR are "plastic".
The new motors works ONLY with Metal Gear.
If your existing cam gear and motor gear are all METAL now...You only need to order a new Motor.
The motor gear and cam gear was made with METAL for decades,
And currently both parts made with metal......
The PLASTIC versions was used for a few years, and the manufacturer quickly learned that was a MISTAKE ..
they should have KNOWN better to substitute plastic gears for the metal in this application ).
the two choices are:
New Motor PLUS a new metal gear = the 3/4" version which is part 7384683
just the motor you would select part 7286039