Here are some articles from old Popular Science magazines. The first article was a large sedan comparison, and there were five. I scanned the part only on the diesel model, the 1980 PONTIAC BONNEVILLE Diesel. The second article was quite an interesting one, which explains the problems GM had and what was really up with these wonderful engines. The magazines were old and dirty and in order to make them readable, I had to scan them in high quality, but just wait for the minute or two and allow them to load -- you'll be glad you did.
Sedan Comparisons..Diesel vs. Gas
The 350 Diesel Page