Don, as of 07, the MADP has the Allison 4000. It was upgraded from the 06, which had MM Chassis, ISL, and 3000. It also has the 1st generation Comfort Drive. That's why there is a significant price difference between the 06's and 07's. The ISM can also be flashed and bumped to 500HP, like the Essex. Several on here have done so. I don't see the need but that's JMHO.
Scotty and Kristen, Airedales Dagny and Wyatt
2007 Newmar Mountain Aire 4528, 450 HP ISM, Allison 4000, 8 Trojan T-105's
2014 F150 4x4 Crew Cab Platinum 157" WB
Roadmaster Blackhawk 2, RVI2 Brake System