Connecting the #2 wire to the BAT stud is not all that bad an idea. The alternator will work, but as the article you reference suggests, the output voltage will be lower. Still better off than the generator that it replaces and the old trucks don't generally have a lot of electrical accessories. Small price to pay for cleaner wiring?
Unfortunately, Jerry's picture is cropped such that we can't tell for certain that the #2 term is connected to the ground stud. Since both wires are black, it's a good guess. I certainly don't like to see more than 1 wire of same colour and size connected to the same component. The proper wire colours, as per GM factory wiring diagram are:
Red to BAT
Red to #2
Brown to #1
Yes, warning light is optional.
