They are listed under terrain, which screwed up my search for the part numbers. That's why I posted them when I found them, so I wouldn't have to search the whole site again.
Ooh, I didn't know that had actual turrets. What Dan and I did for Turrets is that we essentially took a hip actuator structure of a Mech (reseen Rifleman, IIRC), turned it upside-down, and glued weapons onto the ball joints where the legs would normally be. This lets you put Longbow arms for LRM turrets, SEVERAL varieties of gun barrel, and SRM carrier turrets on for SRM turrets. And it was exceptionally cheap because we were parting out kits; something like a total cost of $1.50/turret.