After putting a dent next to my side gill trying to pry it out, I went to the fishing line method and got each side out in 5 min total.
Took a loop of line and slid it around the corner of the gill, on one side it didn't pass so I used my free hand to push the gill in the opposite direction to open up the gap for the line to pass through. Wrapped the other end of the line around a flashlight handle a few times and applied moderate constant pressure. On one side the entire housing popped out, on the other only the corner did but there was enough of it out now to grab and wiggle out.
Was in my garage in 105 degree heat messing around with it for 30 min before I went to the fishing line, but totally worth it. The gloss black gills from IND are sweet.