Just my thought.
When a vechicle is in service with a unit they mod it to suit there needs. My old unit had a turretless ferret that the oc used, now that is not as it came out the factory. We modded our foxes to suit us with extra bins normal off cheftain plus a extrnal gpmg mount. even some of the spartans had a microwave in them. Plus the reme 4 tonner that had a bar built in. So when they leave the army and go for aution all these bits are removed. So when someones buys them and dos them up back to fctory spec thats not as they were. If i bought a sabre or fox it would be refitted back to the spec it was when it was in my troop. Now some of you may say thays not original but thast how it spent its life. Like how meny of you have sen a fox with a copila mount gpmp. Its not orignal but.