Probably a case of just using up whatever armored car hulls they could lay there hands on, and two very popular kits were the Leichter and 8rad, so it makes sense..and they were fast dirty builds, done on the fly for a fast camera pass IMO.
Much like the Needa shuttle and TESB/ROTJ fleet models, just a mish mash of parts for quick passes and background!
Another 8rad pod was half built in fact, you can see it in the Chronicles book in the Tyderium section with Bill George...check in the pidgeon holes on his bench!
lee