HI,
I have heard that this gearbox, although listed as 'sealed' by FoMoCo, will benefit from fresh fluid and filter every 70,000 k or so.
Any thoughts?

Correct. Fluid is a bit pricey but it does get dirty and it is beneficial to change it.

Wait until you buy a filter for it :O

Have serviced E series auto. I would invest in one of those 200 litre plastic containers to drain the auto fluid into and a small tension wrench. Check the procedure for removing the bottom tray. Following the recommended procedure as it avoids damage to gasket The filters for e to AU are around $40 and easy to change. Should inspect the old one for particulates. Hopefully there will be none. Remember to gerney the gearbox and work in a reasonably clean environment. [no sand pits or chook pens LOL]. When jacking up allow a slight fall to the rear. This will directt the remaining gear box fluid into the container rather than where you need to work . A better result is obtained by using a small drill powered pump to remove most of the oil first Good Luck with it

no EA to AU was mentioned. asked re FG 6sp.

Don't get sucked into buying genuine, they are dear as hell. There are two different type Auto pans on 6 speed Auto. One of them is Metal and the other plastic.
Check this page out for filters and Pans much cheaper than Genuine Ford.
https://www.ebay.com.au/sch/i.html?_odk ... acat=33726