Great find, Tom! I love these old miniwagons. Like your uncle, I used to have a similar problems moving my kit around when I used to gig. The best car I had for that were my Azteks, but the funniest one was my Sunfire GT. I managed to get a complete five-piece kit (and my electronics) in that little thing. It was tight as only the driver's seat was not filled with drum or equipment.
I hate to be the pedant, but the 1982 Pontiac J- car was originally the J2000, later the 2000 Sunbird and finally the Sunbird. It seems like every other GM leadership regime since the early 80's Pontiac swerved from alpha-numeric names to actual names and back again.
One these little wagons would be a great little runabout nowadays!