I'll bet it was the one they used in the BG for the interviews on the DVD release.
BTW, I work with Jon Betuel (the guy who wrote Starfighter), and he couldn't believe it when I told him what people were paying for a non-working fake arcade game... Then he told me about the Battlezone he bought a while back, which he had to let go because the joysticks didn't work and replacements aren't made any more. When I told him I could have replaced them for him with newer joysticks, while keeping the original grips, he was like "Doh!"

We actually had a nice little nostalgic conversation about classic arcade games 'n stuff...