Greg is correct, no push-button (pre-set?) tuning on the 1954/55-1st Chevrolet (and GMC) truck radio.
It is still possible that someone cobbed in an earlier truck radio that had push-button tuning. A picture would help solve this mystery. If it is an earlier truck radio, it has decent value.
Here are a few pictures of the one style of radio sold by GM for 1954 Chevrolet trucks (the GMC radio looked the same, except that it had a remote speaker):
1954 Truck Radio #1 1954 Truck Radio #2 1954 Truck radio #3
