I had read about this in a post before over at DP, but I made some changes to the shifts in 4X4 low range(table B) and found out that they change the shifts in tow/haul mode. And judging by the shift points it looks like the tow/haul shifts(table D) are actually 4X4 low. This was with an 02 OS in an ALLISON TCM for the DURAMAX. I switched back to the 01 and I will try and see if it is the same way or not.
OS-15172881 calibration-15172884