I’d literally just replaced the broken plastic bleeder tee and then immediately proceeded to break the coolant return nipple from the top of the radiator, by merely looking at it, it seems. After 15 years and 140k it seems the plastic has turned to mush. I’ve made a temporary fix by threading an 1/8 NPT x 5/16 barb fitting into the plastic and gluing it in place. This would probably work long term, but I’m going to replace the rad and all coolant hoses to be on the safe side. I’m actually glad this broke in the garage and not on the road.