thanks for the replies everyone.
Actually, the directions are incorrect.
The Spider hub is a 3/8" x 1" bolt (not a 5/16"x1). The threads are supposed to be tapped 3/8" x 16.
I tapped it yesterday, but I may call Maco today to see if they can Update their assembly instructions.
I
am going to try to get it up and tuned tonight, before I go out of town tomorrow...
UpDate:
I called Maco this morning, talked to a nice gent named Tom.
He was very apologetic and is sending me a Spider Hub today, so I guess I'll have a spare. I also mentioned that the assembly instructions are incorrect dealing with the bolt size on the Spider, and he said that is also already in work to be corrected.
+1 for customer Service from Maco/Gizmochy-Charles Electronics LLC