Rather than waiting for a new gun for the grav tank, I decided the Red Guard could use an AA vehicle. I scratch-built a pair of gun barrels and mounted them to the turret in a decidedly "up" position.
Yeah, yeah, the barrels aren't true. I'll work on correcting that. I also added a small antenna to the top of the turret to break up the smooth silhouette. It'll be a welcome addition to the Red Guard forces.