The top edge of the fan shroud has two unused mounting lugs, that foul the top crossmember when the fan is presented up and need to be trimmed off.
I must stress, this is really easy - stanly knife, file, angle grinder - pick your weapon - just take it easy so as not to take off too much, or damage the fan; but it really is easy.
The pictures below detail the trimming required.
I'm really sorry about not spotting this earlier, and if anyone would rather bail and send their fans back, I'll give you your money back. That said, once trimmed they really are a perfect fit, and work really well!...
Appologies if this is a pain...
Before:
After:

My fans have also arrived, now all I have to do is fit them.......and put a switch in......and do all the other bits.......