Where to ground amp in back of DC

I've been using the seatbelt bolt, with paint sanded down. I've also been living with grounding problems (buzzing, etc) and cannot seem to find the source of my problem. Is there another area people use to ground the amp in the back of a DC? My amp is mounted behind the seatback of the rear driver's side.

 

i just drilled a hole through the body, sanded the paint off and used a nut and bolt to fasten the cable. you also want to make sure you use a good crimp-on ring terminal on your cable.
i dont have any noise in my system using this.
also be sure to use the shortest length of cable possible
also be sure that your rca wires are routed away from the power wires--- or any high amperage power wires for that matter

 

x2 on the shortest cable length

 

I ran the ground back to the battery and bolted it in where the negative terminal bolts to the engine compartment. No issues.