Which class a motorhome came with a dt466 engine?

I've spent way too much time researching used MDT trucks... narrowing it down to crew cab Freightliners. Never saw one with a DT 466 (like I said above.. a good engine) but I did see way too many with a rebuilt Cat 3126/C7 at the 400K-500K miles range. The Cummins 8.3L/ISC would go in the 700K range with 250-300 HP. Most of the Cats at even 210HP did not make it to 500K.
Not sure why you are worrying about longevity as the average MH only gets 5-7K miles/year so in 20 years 100-140K miles, few enough for even a Cat engine to still be going strong.