The slide is 7/8" ground rod. I used a 7/8" pillow block as the bearing. The fit was tight so I had to spin the rod in my lathe and hit it with 400 grit paper to get a good sliding fit. For rigidity the piece of angle iron coming up off the corner of the table is 3 x 3 with a 1/2 inch wall thickness. It overlaps the table leg by 2 feet and is quite stiff. The rest of the angle iron is 3 x3 x 3/16". Running the head up and down it stays within a thou or 2 but when I tighten the head clamps it moves about 5 thou. I've been meaning to get a torque wrench so I can tighten the head more consistantly but so far I havn't done it. The easiest way to swing the head would be to unbolt the pillow block from the bracket but it would only swing one way. The ground rod could be removed for swinging either way but then the rod would have to be re trammed. The support at the upper end of the ground rod is the same as the bottom one.
I don't know the actual cost. Some stuff I already had. The rod and pillow block were about $40. I spent $250 on the 3/16 angle iron but that included enough to do both the mill table and a flatbed for my truck.
