I think they simply didn't have a stick in their parts bin for the SE. The Tremec/Viper 6-speed used on the RT and SRT is likely too heavy-duty and would have robbed too much horsepower, leaving them to design a new stick tranny for the SE model alone (where else could they reuse it? Charger?). What I don't understand is why they didn't use the Charger/300's 5-speed Autostick.