for anyone wanting to re-calibrate the fuel level sensor on the 26 gal tanks these are the numbers that that i came up with:
Gallons Voltage
0 gal 0.686275
1 gal 0.764706
2 gal 0.901961
3 gal 1.019608
4 gal 1.137255
5 gal 1.254902
6 gal 1.352941
7 gal 1.450980
8 gal 1.509804
9 gal 1.588235
10 gal 1.686275
11 gal 1.764706
12 gal 1.803922
13 gal 1.882353
14 gal 1.941176
15 gal 2.019608
16 gal 2.078431
17 gal 2.156863
18 gal 2.215686
19 gal 2.274510
20 gal 2.313725
21 gal 2.397205
22 gal 2.470588
23 gal 2.529412
24 gal 2.529412
25 gal 2.529412
26 gal 2.529412
27 gal 2.529412
i did this by removing my bed, pulling the pickup unit and sucking the remaining fuel out till dry. i then reassembled everything and while running the scan tool and monitoring fuel level sensor voltage i added one gallon of fuel at a time and took note of the voltage.
i then entered the data into my tune and crossed my fingers. well it tracks nicely, almost exactly nuts on in relation to the odometer.
this is what my {F0101} table looks like now (photo). i did not try to smooth the cells as the ECM/BCM does this already to the the gauge. the gauge still sits on full for the first couple of gallons as the sensor maxes out but there is still room for more.
i have also attached a text file with all the figures for anyone who wants to copy & paste them into their tune