After having a good look at mine I would choose #2 as with other vehicles it always seems to be just the cooler itself that craps out not the rest of the unit, I see the dreaded Tork screws are used as well.... be a prick of a job I think, remove air box and in my case the catch can to try and get some hand room... a ratchet drive with torx heads a must.
Bound to be someone on here who has had the misfortune to replace one...
http://www.midnightmods.com.au/zen-c...roducts_id=288
PS: you will have to give it a damn good cleaning with a good cleaner to get the oil out, if it is allowed to get into the hoses too much they will rot.