Thanks for the replies. Yes, the crack goes all the way through - I added a photo below.
I went ahead and gave the ABS cement a try. (I could not find any markings on the box, but am pretty sure this is ABS because I know the glove box is ABS
and because the plastic seemed to dissolve slightly as I applied primer.)
Based on a recommendation in a thread from ADV
(and also mentioned above by Kantuckid), I used fiberglass tape to reinforce the joint. I first tested on a spare ABS plumbing fitting I had around. It seemed to take pretty well, so I went ahead and did the same on the inside of the top box.
It's pretty cold in my garage today (about 8C / 46F), so I set a light bulb nearby to keep things warm enough and help with the curing.