The A prefix means the unit was built at the MCFA plant in Houston, Texas and is designed to comply with Underwriters Laboratories saftey standards. Often the electrical compnets and wiring maybe different than similar units built elsewhere.

The E prefix means the unit was produced at the MCFE facility in Almere, Netherlands and is built to comply with simialr European standards. This may explain why there was only one part difference.

The absence of a letter before the F17B would mean the unit was built in the Mitsbubishi facilty in Sagimhara, Japan.

Hope this helps.