'12, '15, '17 Tahoe 6l80 3.08 shift schedule comparisons.

[mikez71]

had to tweak some 0% 2-1 downshift and 100% 3-4 shift to get the graphs to be on the same scale.
So one number in each graph is wrong the lighter cells (8.14, 97.29, 97.29)
The actual number is in the neighboring cell.(8.28, 95.94, 95.01)