I found this in H.A.M.B. . My a/c condenser is a remote mounting unit (I think for 18 wheelers) that is mounted under the floor and blows straight down.  It was in a discussion about modifying a Plymouth engine. Hope this might help.

My earlier comment about air conditioning an old car was based on the fact that converting an older car to AC would not generally be a stock application, therefore, the use of an old original unit would not be a good idea. The modern rotary compressor units and the ability to place the modern unit under the dash would provide AC that would be very efficient, and trouble free. Wm.

the link seems to be a joke- it is not: just scroll down!
Greeetings from D?sseldorf!
Go - who is going to take out his Ply for its first fun ride this year!

Just a thought, some of the earlier A/C units were in the trunk and air came up through the rear window ledge. I sure a little more complicated but may be worth the forethought. I think I saw an early 50's Chrysler for sale with one.  The 1956 Chrysler Newport had A/C.  http://www.allpar.com/corporate/airtemp.php.    http://www.imperialclub.com/Repair/Air/index.htm

I would suggest you contact Vintage Air (800 862-6658) in San Antonio, TX..
I have one of their units in my 39 Plym conv coupe, and one in my '64 Chevy C10.. My brother has a Vintage Air unit in his '54 Chevy Bel Aire 2dr sdn.
Nice people to deal with, they specialize in AC/heating units that fit like it is original equipment. Wm.

Did you try Googling Antique auto A/C units and installations?

Living in Florida Air conditiong is a necessity. I own a 1955 Plymouth with a 6cyl. Flathead. I drive it mainly during the winter. Now that summer is here it is too hot and the car sits in the garage.
I have noticed that some have installed after market Air Conditioner set up's in their old cars. Most I asked told me it was installed when they bought the car.
Anyone know of a supplier that sells these units?
Thanks in advance for your answers.