Look up 'carringb' on this forum, if he doesn't find this thread first and post to it. He has an e350 van with a v10 in it. I know it's not a class A, but IIRC he has well over 300,000 miles on his v10 (original, not bee rebuilt), and it's still going strong far as I know. He has towed several different trailers with it, some very large. Great guy, too, I got to meet him once and hang out with him when he was here in my neck of the woods several years ago. Very knowledgeable about the v10 and lots of other things, too.
I've owned two v10s myself, one in a Ford excursion we used to tow a big RV trailer with, and now the one in the motorhome (see signature). Great engine, I really like it.
