It's like a dream! I never had an M984E1, I did have an M984A2 previously but basically the same truck. Angry Detroit 2 stroke 8V92, Allison Transmission, No A/C, Good Times! As for an M984A4, CAT C15, Allison Trans, much more torque, A/C, and doesn't even notice a 23,000 pound LMTV behind...