There are Orks who have looted Imperial weaponry. Not only can they use Space Marine weapons they can also borrow the transport.
A Looted Rhino is an Imperial Rhino armoured personnel carrier that has been looted from a previous battlefield by Ork Lootas and is now used as a transport for their WAAAGH!. These machines are “upgraded” with Ork technology and are capable of loading a group of Ork Boyz. While in battle, Looted Rhinos are fast, and are usually outfitted with a gunner. Looted Rhinos have been used as weapons during many past Ork invasions. However, Looted Rhinos are more prone to breakdowns and often possess inferior armoured protection and do less damage than their Imperial counterparts because of the Orks’ lack of maintenance and care for their stolen vehicles.
Photographs taken at GamesDay of the Forgeworld Display Cabinets. You can find out how I am making my Looted Rhino on my workbench feature.