So I managed to get a flat when bringing it home. One tire won't hold air for more than five minutes. Can't blame that on a previous owner. It was already wearing a spare so I need new tires. D'oh. I did not plan for that in the budget as the size with a white wall is hard to get these days. Doubly so in Canada.
The heater core was bypassed (I knew this but the part is super cheap). It was accessible from under the hood so I assumed it would be easy. Not horrible but not super easy either. There is a giant one piece cover that has a ton of bolts (some well hidden!) and is glued with sealer to the firewall. It would have been much easier to take the hood off but I did not do that. The really long hood hurts here as well it does not open at a generous angle. Oddly this is not well documented online.
Cover off ... eventually.
The new one is significantly lighter not that it will make a difference on the 4000+lb Cadillac.
New heater core in. Since the photo I've re-routed the hoses and added coolant but untested because I can't drive it on the three tires that hold wind.
This arrived (on a Saturday!) literally minutes after I buttoned up the repair. Flicking through it I have to say its on the poor side for a Haynes manual unfortunately.