Sorry for the delay. Cell signal is not what I wish it would be and thus goes my efforts in a quick reply... :( Well I am unsure about exact diameter but I believe it to be about 1 Inch. Well here is the specs from the seller:
Travel: 96"

OAL: 105.63

Thread Length: 99.41

Thread Dia.: 40 mm

Thread Pitch: 40 mm RH

Nut Length: 3 3/4"

Nut Dia. (body): 2.870

Nut Dia. (flange): 4.580

Bearing Dia.: 1.181

Coupling Dia.: .9845

The motor kit I was looking into has 1 hp servos. Unsure at this point if I need to go larger. I know inertia, torque and other details have a big impact on the screw size. I am just unsure if my choice of electronic equipment is lacking. Some guidance is what I am looking for. Thank you all for your time.