Refrigerated car question

[foulrift]

The food warehouse that I am currently working on is going to require a reefer to deliver meat and produce. I took one of my 40' box cars and added hatches on the roof for icing but my main concern are the side doors. Did steel reefers ever have sliding doors? Most of the pictures that I have seen shows doors that are two piece swing doors.
Any information and suggestions would be appreciated.
Bob