First time I’m doing this so my question is on the drivers fender there a ground that nut is rusted that grounds to body can I use penetrating oil on it to loosing it up ? Should I unhooked the battery before cleaning up any grounds ? So there is one on the core support and on top off the transmission any more? Thanks

 

Pentrating oil is OK, no need to worry about the battery when playing with grounds.
https://www.chevyhhr.net/forums/how-...cations-56504/

 

Just make sure the wrench doesn’t touch any positive terminals, like the starter or alternator or the fuse box lug.
I use a plastic handle stainless steel bristled brush to clean the ground studs and wires

 

You would be best to get some ground strap and cable and do new ones to the body at fender/rad support, firewall, frame rail and rear panels.