this is by no means an exhaustive list, but it covers some of the most common, and potentially expensive faults you may encounter on a 75.
electric sunroof, they've a habit of not closing.
electric windows. see above.
alfa control unit, prone to random lights coming on for no reason
in fact, typical alfa, pretty much all the electrics.
check the rear wheel bearings, they can be expensive to replace as they need to be pressed in at a machine shop.
if possible, check the propshaft donuts (3)
check brake operation, including handbrake. the rear brakes on the 75 can be awkward to adjust if you don't know what you're doing. my first 75 had dreadful brakes til i got them adjusted right.
if it's red, expect the colour to fade faster than you can polish it !! in my experience, the alfa red can fade to around 8 different shades on one car !!
check for peeling lacquer
most common areas of corrosion ;
front and rear jacking points
front chassis legs
around the engine mounts on the inner wings
around the arches, quite often hidden by the plastic over arch
inside the boot, around the floor. also, peel back the carpets & check around all the seams. there are a couple of blackspots in there, but i can't remember exactly where ? maybe someone else will point you the right way ?
also, the 75 has very little ground clearance, if memory serves me right it's only about 3 inches ?
this means the exhaust could have been rattled off every speed bump from here to kingdom come ! have a check & make sure it's not held on by a wish & a prayer !! a hard bang could potentially crack the manifold.
i'm not aware of any major mechanical failings of the twinnie ? check for good oil pressure, although this may not be possible, it'll depend if the gauge decides to work that day !
syncros are prone to wearing, you may have a crunch if you change 1st to 2nd, or 2nd to 3rd too quickly
parts are readily available should you need them, and they're no more expensive than any other alfa. performance parts are out there too, i love 75's, and i'd happily have another one in a flash. it's a great car to drive, comfy, reasonably frugal for a 2.0, and above all, they go like stink ! the lsd means you can steer the car on the throttle too. great fun !!