I'm really surprised at the measurement between the stays on your CT. There was definitely a frame change after 1959 using your Wasp frame to compare. When and if you/we find out what the A stands for, you're still up against the odds of finding the right fender. From the catalog specs that I have access to, the only bikes that used that 5200A fender is the CT and Wasp and during a certain time period of possibly 1960 and later. Having all the critical dimensions will be the only for sure way you'll find the correct fender since most sellers have no clue of what they are selling. Here's an eBay example of what might or might not be a later Wasp fender. The seller basically indicates it's for every balloon bike Schwinn made.
The fender is the original Schwinn big deep fender used from 1946 through the early 1960s on Schwinn Ballooner, Heavyweight, or Fat Tire Bikes that had 26" x 2.125 Tires and wheels. What we have for sale will be listed!Need other Schwinn Parts?.
www.ebay.com