Negative ground
red is positive on a negative ground system
Negative ground.
Negative ground.
The system is negative ground.
it has a negative ground system.
Some never used positive ground and always had negative ground. The last year that I know where positive ground was used was in 1969 when Jaguar switched to negative.
The Suburban has a negative ground system.
Post the year, make and model of the vehicle (in new question) and one of us can tell you if it is negative or positive ground.
Batteries are neither positive nor negative ground. It is the circuit itself that determines the common ground. For example: If I have two circuits, one needing 6vdc negative ground and the other needing 6vdc positive ground, the battery would be installed the same way in both circuits (positive terminal on the battery to the positive connection in the circuit, regardless of whether the circuit is positive or negative ground). The reason for labeling the ground as Positive or Negative has more to do with how the circuit is wired up, than the actual voltage source. The explanation for that is beyond the scope of this answer.
Electrical sytem positive ground
Yes, the electrode holder (stinger) is positive and the ground is negative which means you would be welding DC positive.