I was hoping a $5 package of JB Weld would save the day, but it did not. Cured for 24 hours and split apart as soon as the system got up to temp. Apparently the plastic expansion tanks on the rad are made of JB Weld kryptonite. Who knew?
So...gonna have to replace the radiator in the Olds, soon as it warms up a bit.
Looking online, I'm not sure how to tell what model I need. With or without engine oil cooler, transmission oil cooler, low coolant sensor, etc. I'm pretty sure I've got the low coolant sensor, as that is one of the warning lights that illuminates in the ACC position.
Is there is a quick way to tell without getting under the car in the very cold and tracing all the assorted lines, I'd be happy. The tip of my nose would even thank you for not having it nuzzle cold metal.