Bob's 56 Buick tempted by sign???

Bob look at the billboard, and the car being advertised seems to be similar if not the same as your '56

 

 

 

......now checkout the Billboard:

 Fairly close .........though maybe a year apart,.yours also looks like an Oldsmobile,my oldman had an Olds with simialr tailights up high on the fender like that.

                                                                                          HF&RV