So what happens when a car manufacturer puts a truck bed on one car model but not on all the other models based on the same platform? Madness, that's what happens! Here's a very nice Buick GSXamino (dubbed the "X-Camino" by its owner), built by a guy who wanted to go fast with class and haul bales of hay in the back. Say what you will about the sacrilege of making non-Chevelle A-Body-aminos, but I think the GSX-amino actually works (though the combination of Stage 1 455 and zero weight over the drive wheels might make for some hairy handling hijinx).
The X-Camino [Classic Car Interiors]
Fun With GM A-Bodies: El 442 [internal]