there should be 3 resistors. 1 between + and the can, 1 between - and the can, and the 3rd should bridge + and -.

on every single motor like this I have its the same setup, looking directly at the endbell, the resistor between + and - passes OVER the motor shaft, and + terminal is on the RIGHT side.

as for getting hot. what gearing is on the truck? the MTs would need slightly smaller pinion due to bigger tires (if they're stock tires) Is there anything binding in the drivetrain? could just be a bad motor...