Question on condensing unit mounting

[600SL]

I have a question on mounting the condensing unit for my 3.5 ton Goodman heat pump. There doesn't seam to be any access to holes on the bottom of the unit without taking apart the whole thing and drilling. nor does it appear that the pad I have has holes in it to mount to the concrete but I could drill those.

Is it standard practice to just sit the condensing unit onto a pad which is sitting on concrete. the attached photos show my pad and condensing unit.

How important is leveling. I could get the unit level by shimming 3/4" under one side of the pad but that would leave a bridge area where the pad may sag over time.

 

[zmaxmotorsports]

There's probably clear tape on top of those black pads,peel them off after getting pad level and,set the pump down on it.
I like to put something solid like rock under the pad after making sure grounder is level.