When I turned 16, My grandpa gave me his first car he bought brand new off the lot in 1964. It had a 352 Police Intercepter engine that came factory with a 3 barrel carburetor. I posted this car on many pages and had lots of comments on cause of the 3 barrel carburetor. A lot of mechanics that been mechanic's all there life tell me there is no such thing as a 3 barrel carburetor. They tell me maybe it was 3 2 barrel carburetors. But I'd say there is only one. Then mechanics said there was only 2 barrels or 4 barrels and had me thinking that maybe it was not a 3 barrel. So I looked into it and found that there were 3 barrel carbs built in the mid to late 60's. 
Holley made 3 barrel Carburetor's for a few years. 1968 Plymouth Roadrunners I found out had 3 barrel carbs too. The 3 barrels were made for high output engines like police car engines. Now 4 barrels replace them.
Cool first car man!
Thank You
Interesting I did not know that, the post was educational and the old Ford looks great. Good job!!!