I have an FK402 AE finder for the 645 Pro and Pro TL for sale. In very good condition.

The AE Reflex Finder is an Aperture Priority AE (auto exposure) eyelevel finder. It features red/green LED readouts and offers center weighted metering in both the auto and manual mode. Blinking indicator gives under or over exposure warning. Convenient +/-5 diopter adjustment and rubber eyecup is built-in.

I originally got this to replace my non metered prism, but I found a good deal on an AE prism.

$100 plus shipping.