The holes are drilled in the center of 7/8" round bar on my vertical mill and then the rocker shaft offset and height I want is milled with a 7/8" round nose mill end. Then they are cut to a rough length with a hacksaw, placed back in the mill in a small fixture, machined to a finished length and deburred by hand. With my crude tools it is huge time consuming pain in the arse and the reason I only do them for myself. Then you still must make the offset drilled hold-downs. With the labor time it takes me to make a set I'd have to charge $1,000.