Do I have a 1920 or 1945 Carb.

I have a 1973 Dodge Dart Sport slant 6 225 which I believe is all original. I don't know whether it's a
1920 or 1945 Holley carb as I believe they switched over near the 1973 year. I'm trying to get a carb kit for it.
The numbers on the side are 6594 1313 and below that 3698347. Any help would be appreciated.

Thanks