Armored vans used by the kat resistance fighters in the future. One of them contained a portable laboratory for Professor Hackle. By the time the SWAT Kats arrived in the future, the resistance group was down to three, including the portable lab. The one used by Feral and Felina was destroyed in an attack by one of the Metallikats’ robot choppers. Callie and Manx’s van was captured after hitting a tree and put in the back of the robot chopper to be flown to Metallikat Headquarters.
These vehicles are recycled designs of the prison van from Chaos in Crystal. It’s possible however it’s simply a common type of van in Megakat City.