Second connector , first picture , wiring is in the neighborhood of the air dryer, and could be for the heater portion, but not positive , because my coach has a different brand of air dryer.
I downloaded , rotated and enlarged photos.
The third connector , second photo, appears to be on the trans bell housing , and that could be part of the Allison trans wiring to the sensors.
Examine the on trans harness closely , early Allison transmissions used 3 sensors, 1 input speed sensor on bell housing ; 2 output speed sensor on the tailshaft; and a third in a central location , drivers side of the trans about the middle; then the third sensor was discontinued BUT the harness continued to be produced with the wiring and connector for the third sensor . The sensors can be interchanged for testing and the connectors are the same .
Check your harness carefully , if the third sensor connector is there , you can cut and cap the wiring and transfer that connector to the input speed sensor.
99DSDP 3884, Freightliner, XC, CAT 3126B, 300 HP /ALLISON 3060
2000 Caravan toad, Remco & Blue Ox.