Got the new cooler installed. No leaks, so at least I know it was the old core that was bad.

With all my tin cut away it is easier to get in there BUT...

My -10 oil lines make it impossible to get to the cooler without pulling the blower housing. My air flap is screwed down to the oil cooler duct so...

I have to pull the rt side tin in order to unscrew that flap. If I drill a hole in the tin above the screwhead, I may be able to access it without taking it all apart. Didn't take that long to do the job. No way I was going to drop the motor after just getting her in again, I still would have had to pull the housing and tin off anyway.