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!
A kid in my high school (in the 80's) had an Astre wagon with a 400 small block stuffed in it. The front shocks were very worn or not there. He could hit the gas from a stop, let it bounce, then hit the gas again and pull the front wheels off the ground. Our neighbor had a Pinto wagon with the little portal window in the back and 302 Boss motor with C6 trans. Every morning when he started it to go to work, it was like music. He offered to sell it to me. He said it would be a great car to drive to college. I was not interested in Fords. Like an idiot, I passed.
I have a 1978 Sunbird Safari Sport wagon. It has every option except dash gauges and the V-6. I love it. Turns heads at the car shows. I even get some best of show trophies because nobody has seen one before. Took it on the Hot Rod power tour. The old 2.5 did the job. 70 hp of fun.
In 1978 my wife and I bought a 76 Vega estate wagon in bright yellow with wood grain trim and roof rack. The car was virtually new with 5000 miles on it. We hauled two small children and small dog around for 150,000+ miles in that underpowered little economy car. Changed the timing belt every 20,000 miles after the first one gave out at 18,000 miles. Cute but slow. We had to get a "runny" to make it up steep Pennsylvania hills . We still laugh about that car.
Bought a '73 Vega Hatchback off a buddy from high school (way back in the day). He had installed a 300HP 350 & suspension/exhaust to match, but nothing else. (Stock trans. & diff). Even so, I burned off all the 13'' tires I could beg, borrow, or steal! LOL.