Where is the best place to buy a condenser and drier for my 71 Cutlass??

 

Four Seasons Air a division of Standard automotive Products

 

If the other recommendation doesn't work, try Classic Auto Air in Tampa FL. They have just about everything you would need for your AC system. All of the aftermarket condensers will not have the same appearance as the OEM ones. Just be careful what you buy and stay away from the Ebay ones that are listed as "Judging" quality as they are not. You want to make sure the line that connects to the receiver drier is at the same height as your stock one. I believe you will find your stock location to be about 5" down from the top of the condenser. Some of the repop ones, including the Ebay "Judging" ones, are only 3" fom the top which causes a problem securing the clamps to the receiver drier. Namely, the lower band clamp will not be in contact with the receiver drier. Just double check on that dimension before buying anything. If you need to have something that is of factory appearance, you'll need to get a decent used one and CAA can restore it. I'm not affiliated with this company but they did work for me and I was very pleased.
Brian