wholesale transformation - like an all different suspension/steering and/or an all different drive train?
A Panel with a different suspension or drive train is still a Panel. Its basic essence or identity is still intact.
Again, the cosmetic surgery analogy: If my wife gets a tummy tuck, that's an improvement that still leaves her basic self intact. Ditto for driveability improvements on a vehicle.
But if my wife gets an entirely new face or body to the point where she's unrecognizable as her former self, well that's just extreme and weird. Ditto for changing a panel into a Suburban.
I mean, how would most guys like it if their wife suddenly looked like Jennifer Lopez? ;-)