I've just received a mid-series instrument cluster out of an ef xr6.
I got it for nothing so i don't really care if it's stuffed.
What it does is the odometer while driving will clock up, but once you switch ignition off, and go to turn the car back on, it will reset to 44,555km. I ran it up in the bench in the workshop so i could wind teh k's up to suit my cluster but once you remove ignition, it'll reset.

I'm thinking it's the EEPROM, can anyone confirm this or know what else it could be?

Oh and the low coolant light flashes even with the sensor plugged in (brand new).

I lost count of how many EF/EL clusters I changed when these cars were under warranty because of odometer problems. Most of them would get to a certain number, like 39,999 and then go back to 30,000km!
Ford's fix was to simply replace the whole cluster. There should be a way of fixing the internals.

do you know what part fails?
i'd hope it would be the eeprom, but i don't want to rip mine out of my current cluster if it's not going to fix it.

Not sure on the exact cause. Maybe these guys can help you http://automarineinstruments.com.au/

You can use components from the XR cluster to upgrade your std cluster - IIRC 16 surface mount (resistor/cap), 6 mounts for the upper gauges, and the VDO IC, you can test all the components with a meter, there's plenty of duplicate components on the board as well - the VDO IC doesn't form part of the odometer part so shouldn't be at fault.
I upgraded a GLI cluster using a wrecked Fairlane cluster this way about 9-12 months ago, and surprisingly, it was fully functional, and still is.

Obviously, you need to be a decent solderer, and have the gear to suit, should take you about a day to do.
Probably not a preferable option, but it can be done.

An interim option may be to source another eprom from a wrecked cluster (or a cheapie cluster off Ebay) and install it on your XR cluster, to see if the fault is cleared.