I might then guess, Bill, that those WFEX cars were built in 1955.
The WHIX cars, all with identical ends, were built in three orders from PC&F in 1952, 1953, and 1954-1955. There are photos of three of them in Classic Freight Cars Volume 3. I will send you my files Tony so you can see what the ends look like. I don't have the photo that Bill mentioned.