I ordered and installed this control lever (driver's side). The anti-roll bar holes on the underside of the wishbone are pre-drilled but unthreaded. I have decided to order two new stabilizer bar bolts (GM P/N 15592554) and a new lower control arm stabilizer bracket (GM P/N 15677617). When the new screws arrived I found they were 10mm and had a 1.50 thread pitch. So I cut holes in the lower hammer control rod of 10mm (1.50 thread pitch). . From the looks of it, the quality of the control lever is OE quality. So far this product is working well.