Parts availability is is hard and getting harder for 8.2 fours stroke DD's. They were not popular like the 2 stroke DD's and had a bad reputation for Cylinder head problems in the earlier years. GM went from 13mm to 14mm head bolts and redesigned the heads and gaskets. Apparently this engine was designed for busses, and had problems from the start.
Marinized versions didn't have as many issues perhaps because of the constant speed, constant load service. I had a set in a Monark 32' work boat. Several lobsterman friends who used them had better luck with theirs than I did with mine.
The one redeeming value that they did have is they were VERY fuel efficient, hence the "Fuel Pincher" name.