Ed & David,
In RAVE Rover states:
"Use Texaco N402 or equivalent". I understand that to mean a container branded with the Texaco logo and the ATF type N402. A club member wrote to Chevron (the OEM company) who said that they no longer manufacture Texaco N402. They offered a current product, Texaco Havoline Multi-Vehicle ATF, which is suitable. We cannot argue with the OEM about that!
We don't know who manufactures MGR/X-Part VYK 000040 but if my memory serves me correctly Chevron said it wasn't them. So, strictly speaking, VYK 000040 isn't any more 'correct' than Carlube ATF-U or Havoline Multi-Vehicle ATF. Since the original Texaco fluid is no longer available, they are all 'compatible' products because they all meet the required specification: Texaco N402. This is all that matters. ATF-U might meet other standards as well but that doesn't make it any less suitable or inferior to VYK 000040.
When it comes to lubricants people seem to be very passionate about brand loyalty, and that's entirely their choice. I guess that the marketing people have done a good job.
But as far as engineering considerations are concerned, if it meets N402 spec. it's fine!
Simon