Due to lack of components, the 140CPU53414 went through a re-design and that's why the part number changed to 140CPU53414A. This redesigned version of the controller was designated with an "A" at the end of the part number. This version is functionally identical to the standard version (non-"A").
However, If you are using the module in a hot standby topology, then you must use either two non-"A" models or two "A" models.
However, If you are using the module in a hot standby topology, then you must use either two non-"A" models or two "A" models.