Folks,

I've got my old steering box in bits at the moment to replace the sector shaft lower seal.

There's an exploded diagram in this thread of a TD5 steering box.
http://www.landyzone.co.uk/lz/f8/leaking-steering-box-69039.html

In the diagram it suggests that there are two seals.
Item 8: Seal, washer and backup seal.

Have the seal parts changed at all?

My box has seal->washer->circlip->outer dirt seal

No secondary seal by the looks of it?
The next thing above my seal->washer->circlip->outer dirt seal is a torrington bearing.