I would agree with John I have owned four Foretravels and would not own a coach without a retarder. Yes it is a Allison on they build a huge cooling system to cover all the heat reduction necessary. After over 75000 miles with retarder you will not be disappointed.
The Foretravel chassis is the same on the Phenix and the IH. The coaches are essentially the same but height. Both come 45' both have or had the Cummins 600 ISX. Bothe are custom built and if you look at the web sites, both have the same specs except the floor on the IH is flat but on the other it has a step as John said. I appreciate that you want to talk to a IH owner but a Phenix owner who has had 4 foretrave's who could have bought a IH but the height was an issue in my garage. The front caps are diff the rear ends look different but other than cosmetics the can both are custom built and there are no limitations as to options between the two. Bothe in addition have travelride suspensions, in,00dependent front ends glass dashes etc. My 2008 has never been down with a problem other than the usual maint. Of the four I have owned the quality got better each year. The thing is my first coach is on its third owner and has 125000 miles looks good as new. I do believe they make the best fiberglass coach in America. when you go to the bus conversions and Newell you are changing the build comparison. I hope this helps.