As we know and per the ZF Factory Service Guide:
Our LR4's come with the ZF6HP28 with the plastic pan.
From the ZF Spare Parts Catalog:
The ZF6HP28 and ZF6HP26 use exactly all the same parts.
From the ZF6HP26 factory service guide, the 26 comes with a plastic Type A or a steel Type B pan.
The steel pan is supplied to BMW, Lincoln, Audi and Bentley.
The plastic pan is supplied to BMW, Ford, Hyundai, Jaguar, Lincoln, Alpina, Aston Martin, Rover, and Weismann.
Because all the piece parts are the same, this is what allows the pan swap out from plastic to steel.
The plastic pan has only a drain.
The steel pan has a drain and a fill, both in the bottom of the pan.
From the ZF factory service guide:
Here is a cross section of the fill from a ZF Training Presentation showing the Bentley.
And finally, I have in hand the steel pan as sold by AB, it is ZF part number 1068 203 020.
The pan is an exact match to the various drawings above and comes with a BMW sticker on it.
So the question remains, when going to the steel pan, do we use the fill port in the transmission housing or do we use the fill port in the bottom of the pan.
This only becomes important
ONLY IF there a volume difference, i.e. is the fill port level actually at the same elevation in either case.
As above I have conflicting posts, one that says there is a volume difference, and if I could find it, another that more convincingly says that there is not.
I plan on sending this comment to ZF by way of explanation of what we Rover geeks are doing and to ask the question to the vendor.