I placed my ZL1 addons jack pads in the furthest front opening. The "middle" opening is the jack point for lifting the entire side of the car. I use one of
these to jack the car up using the middle point, then put the jack stands under the pads on the front and back on that side. Repeat for the other side. The grove in the Dewhel's appears to be the same depth as the ZL1 addons pads. Just make sure the pads are flush up against the frame when tightening the allen bolts. I bought a longer set of bolts on
ebay so there was more of the body of the bolt left in the hole after tightening. As others mentioned, use some blue loctite on the bolts before tightening them so they stay put.