Detroit Diesel 8.2 Parts

My dad is looking for the marine-specific parts for 250 HP 8.2 so that he can have a spare engine completely rebuilt and dyno tested the bench.
Specifically, I think he's looking for an exhaust manifold, intake manifold, bell housing and flywheel.
Does anyone have a lead on these things? He would probably also buy a wholely rebuilt engine if it came with a warranty.
FYI- He's located in Southwest Ontario on the Great Lakes.
Thanks for any help.
Ken

Problem with the old one

As an aside...
The reason for the replacing the existing engine is a strange one.
At the beginning of last season, one of the engines started to severely leak oil from the rear main seal. He rigged a sump-pump to recycle the oil until while he weighed his options for replacement. After a couple of days of running like this, the problem corrected itself. So, he continued to run the engine daily for the remainder of the season.
This year, the problem has returned. Is it possible that this has something to do with a stuck valve as a result of sitting dormant all winter?

I think he's in the process of replacing the rear main seal this evening. He called me cursing up a storm this afternoon

The swearing is over. Main seal wasn't seated properly and a new one has been installed. My dad and little brother did the whole job themselves- gotta love Canadian ingenuity. Especially the sump pump I mentioned earlier. My dad placed a plastic pan beneath the transmission to collect the oil leaking from the seal. In the pan was a pump with a float switch that would recylcle the oil back into the engine.