I have one in my car too. The price is the same no matter who sells them.
I suspect the '55 and '56 full-sized cars originally used vacuum powered wiper motors, could be wrong, and I don't have a parts book to see if they used different wiper motors for the two years.So....no one knows if a 56 wiper motor will fit into a 55? If the 55 has been converted to 12 volts?