Gargraves are 3-rail.
Unless you are doing something funky with one rail, you do NOT need reversers.
You can install them however you want, but they will never engage and swap polarity.
If you do what the previous poster said and draw out the inside rail, outside rail and center rail, and look at how your track is built, you will see that the center rail is always the same (Ground or hot). And both rails are the other side of the circuit. As in up through the rails (either or both), back through the center rail.
The turnouts are very clever and specific that the center pickup will not touch the outer rail. And if it does short momentarily, that has nothing to with reversing loops.
And three-rail cars usually have no insulation on the wheels. So the outer rails are shorted just by the car being there.
So you lucked out, no extra wiring needed.
I once had a Marklin layout, which is also 3-rail. Figure 8 with shunts on each side.
A Lok could go in one direction, then reverse, all without issue or reverser.