E350 460/7.5 Rear Heater Hoses Question

Trying not to post same question in two forums, but there are more "engine type guys" here than in the Class C forum. So if anybody here knows something about my question there, please jump in on the Class C one,
Thanks

http://forums.trailerlife.com/index.cfm/fuseaction/thread/tid/29737640.cfm