1 - LB7 (2001-2004.5)
2 - LLY (2004.5-05)
D - LLY/LBZ [note: The LLY of these years is actually an LBZ with different tuning. So check the build date (IIRC on the drivers door) before you buy. IIRC, the switch was in Jan of 2006.]
6 - LMM
Allison trannys were 5 speeds 2001-2005. 2006-up are 6 speeds with tap shift.
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