even though the information you showed for the controllers being 36/48v you might want to double check the tags on the motors themselves and see if they are dual voltage motors.
I have seen some dual voltage trucks that even though have the dual voltage oscillator cards they only come with the voltage rated motor the truck was ordered with, being either 36 or 48v.
If and i stress IF... the motors are dual voltage marked then all you need to do is make a couple of adjustments/verifications in the oscillator card settings and adjust if needed (usually there are two different setting ranges for either voltage that determine current limits and other settings amp/load related, and THEN check the service manual throrughly to make sure there are no jumpers in the harness that need to be switched.