I've had a look on Realoem and the only thing that I can see 'seal/gasket' related are no's 3 and 16 here: RealOEM.com * BMW E53 X5 4.4i timing gear timing chain top - VANOS Is no. 3 what you are talking about?

I just want a better understanding of how these things go together and what is needed, so that I can talk to my friend next week, as even though he is good, he MAY not know as much as you guys/BMW techs know and may NEED to know. Or at best he WILL know and I can then have a better understanding when I discuss it all with him!

Thanks again James, for your time and input in all of this.