Getting prepared to dive in when the time comes; don't see a site with a nice interface that allows to drill down to individual diagrams and part numbers yet - so far, I see sites with small pictures and not much search capability.

Something like this - here, you enter the VIN and get the diagrams down to dealer options (this particular car has a non-standard factory spec'd LSD): https://www.realoem.com/bmw/enUS/par...--E28-BMW-535i

Where do I go when I want to get as deep down as it gets?

 

I use this one which is for some reason on Jag Land Rover Classic's website, and then copy / paste part #'s to the dealer sites (usually landleaping.com which is Land Rover Portland) to purchase.

https://parts.jaguarlandroverclassic...nd/land-rover/

 

...and thank you for posting the link to the shop manual as well, that's priceless