I have a 1998 HR Endeavor 34' with the ISB 275 hp and Allison. I just got back from Quartzite, a 500 mile roundtrip. I had an easy drive at 62 mph with cruise control on most of the way. On any grade between LA and AZ up to about 5%, the trans would shift down to 4th but held at 60 mph. I got real close to 10 mpg over the trip.
When I take the hwy 101 over the Conejo grade going up the CA coast, which I think is about 7%, I do drop to 45 mph and hold that speed.
For me, this little package is the engine that could and does.
