Well, we got it fixed. The muffler is actually a Fleetguard part - #86542M (Fleetguard Exhaust) as are the hangers, connectors, C strap, etc. Dave had talked to Andy at Cummins in Yakima who took the measurements and found the part number for us, and then had us call Cummins in Sioux Falls (where we were headed) who ordered the parts and got it in today.
Couldn't see any part numbers on the original - they were probably located where the holes were!
Barbara & David O'Keeffe
Figment II (Alpine 2002 36 MDDS)