The mounting template on 9-2 is correct for all those dimensions.
Page 2-6 is a planning guide. Since the battery is not rectangular, the dimensions on 2-6 are a bit of a rounded up estimate. It does appear we rounded the 3.118" to 3.30" instead of 3.20". Not sure if that's a typo or if we had a reason.
The 2.1" is correct, I just checked it with a caliper, as well as the 9-2 dimensions.