so its something that is not grounded at all or? How can it be grounded wrong/bad?
Corrosion & vibration will mess with the electrical connections, both (+) & (-). Those are 19-20 years old now, on your truck.
The ground that is usually the first to go bad/break is the braided one that goes from the body to the back of the engine.
I'd suggest doing 'The Big 3'. It's more efficient, so it's easier on your whole electrical system. At the age these trucks are now, that's cheap insurance. If those are the original cables, they probably need replacing anyhow, so why not do it right, once?
Grounds are important. The electrical system is only as good as it's weakest point. Grounds should be as large, or larger, than your power cables.
I'm not a fan of grounding stereo systems to the seat bolts. That's an environment that is prone to moisture (the beginning of corrosion) & all the dirt & other stuff that can work it's way into that area. I prefer a dedicated ground or run that right back to the battery.
When you check the cables on the truck now, if they are showing that green/white corrosion at the ends, I wager odds that that runs the length of the cable inside.