Ground for amps behind cm back seat

Moving all amps to the back wall of 2019 crew max. Where is a good ground point back there?

trying to make sure I don’t have any alternator whine.

thanks. And if you have pics of your ground can you post.

 

My 2 cents. Someone may recommend under one of the rear seat mounting bolts, seat belt bolts, OEM subwoofer mounting points or under the tire iron kit holding bracket, however, folks have encountered whine in those areas. There's also a ground behind the rear panel that feeds the rear window motor but it's not readily accessible in this scenario. Another option is to attach to the chassis, but again not readily accessible in this scenario. If you end up with whine, recommend using a Ground Loop Isolator which is inexpensive and should resolve the issue.

 

The only grounding you’ll have anywhere in the interior still has the weak link of the 6ga (or is it 8ga?) body ground connection between the battery and inner fender, plus the braided ground strap from transmission to body that likes to corrode out and break.

Are you running a 4ga power cable back there? Then run a 4ga ground from the battery too, it’s every bit as much of the circuit.

 

OP PM'ed me but thought I'd share here for anyone else in the same boat. Factory ground point behind the driver's side C-Pillar trim works fine. Remove the seat belt bolt and panel held on by trim clips. Other option is to go through the floor pan directly to the frame. There are grommets underneath the carpet/foam.

Factory ground point I'm referring to:

 

So I tried them all and I finally wound up grounding on the stainless steel seat bracket. That’s the only place I could kill the alternator whine. I tried the ground behind the seat belt and then the seat belt bracket bolt and finally the seat bracket itself. I’m going to cut out a small section of the styrofoam and ground to the side of the seat bracket. Should be the bees knees. Thank you all for your input and help. Lot more info for others to eventually find and try.