Somewhere along the way in my reading up on the "SSI" replacement/backdating heat exchangers was some commentary about the different grades of stainless used in different parts by various manufacturers. Now that I think about it - and with a few more sips of coffee - it was/is right here on Pelican:
Porsche 911 (1974-1989) - Heat Exchangers and Hoses - Page 1
Anyone familiar with how these Eisenmann heat exchangers stack up on that question?