update. (for the benefit of anyone else and reference for myself)
i spoke with the mob i mentioned above, and their techs are really knowledgeable and friendly to deal with (unlike 85% of the gmh / hsv dealership/parts place ive rang so far).
i was told that were upto 5 variations of the ISS system used in the production runs for the VT s1 HSV's (A,B,C,D,E etc).
each one uses 3 various points to immobilize the car (ignition, ecu, fuel pump etc etc) also, i was told some models of the ISS are no longer available as genuine parts (matched by part no#'s) <- if i get any more info, such as the revisions that are no longer available ill post it.
the revision of the ISS used in the car can be identified by getting the VIN & asking someone at HSV. (apparently if you know who to call, its easy to get this info)
once you've got that info, its matter of finding out if someone can source a replacement ISS module to match the existing one - otherwise...
if you cant source a matching ISS system, you 'can' get one of the other modules, however the wiring from the module is slightly different (due to the different immobilization points) and you have to individually solder each wire from the existing ISS loom into the board on the ISS Modules.
(^ i cant quite remember exactly what he said.. will clarify tomorrow if im wrong now, but im guessing a good auto elec will sh!t this in)
I have a factory installed/approved aftermarket alarm, so Im kind of forced to fix the ISS system in order to keep that in place - whilst im sure the alarm may die one day, at which point ill have to get that ripped out as well, but for now - im stuck with it
Ball park cost of just the system is $800 - so for those contemplating buying a VT HSV (s1) - for the love of god, make sure you get red & black fobs with it!
UPDATE 2
ok, so i was told i have the 'B' system, and holden no longer make the iss module as a spare (came up as not available when queried).... this means that im pretty much screwed (coming from a group that have alot of knowledge about the system... that doesnt fill me with confidence ill be able to sort this out).
However - my local mech (top bloke) is contacting HSV on tuesday and will see what comes back (DAMN Monday for being a public holiday!!! - nah not really. long live the queen!)
I also, did read elsewhere (cant find the freeking link now.... typical - that someone had the same issue with a monaro, but because it was only used on a track, removing it wasn't an issue - hopefully this means i can get the whole bloody thing removed somehow).
i'll be sure to update for as long as the saga continues.