I have a 410DA with cat diesels. I have not replaced the water heater yet but it should come out with removal of the exhaust elbow. Posting a picture would be helpful.
Sawzall, take it out in pieces if you can get the replacement in without the obstruction. Or relocate the HW heater in a new location that makes more sense for serviceability.
Have 1998 40 DA with diesels. Previous owner hacked up the old to get it out. Replaced with Isotemp Slimline which slides right in. It’s only 4 gallons, but you still get one long shower out of it. 2nd person has to wait about 30 minutes.
