So i've been doing some further research, including getting in touch with Renault themselves. The correct Alternator can be sourced from Renault (shipped over from France) but they want over £400 for it!
So I've done some further searching, and found some suitable cross reference numbers. I've confirmed the original Renault part number (from my list above) is: 77 00 780 774.
This cross references against a ton of other manufacturer's units, but the cheapest i've found is the CEVAM unit, which can currently be picked up via Ebay, shipped from France at the following link. The CEVAM part number (included for when the link goes down) is "4302".
http://www.ebay.co.uk/itm/191696513399?_...EBIDX%3AIT
Obviously, the pulley on it will not be correct (unless you believe the fact the advert advertises is as coming with a "V belt" pulley, even though it contradicts itself again by specifying 5 ribs), so this will need to be changed. I don't have the shaft diameter, or the method of keying required for a pulley to fit the unit, but as far as the pulley is concerned, it needs to be a 10mm wide pulley to accommodate the 9.5mm width of the belt (cross reference belt - Gates 7495 used as an example) and a 36 degree wall angle in the "V". I don't know what is typical for a pulley diameter either i'm afraid. But does it matter? I'm not sure.
Perhaps a pulley kit for an old Lucas alternator like the below link, will fit?
http://www.ebay.co.uk/itm/LUCAS-FAN-AND-...Swp5JWXtfV
Ultimately, it requires someone to have faith and to buy one and let us all know how they get on with fitting it. I'd do it myself, but i'm a bit hard up right now, and don't actually need a new alternator right now. If anyone "goes for it", then please....give some feedback and let us know. I've done the hard bit narrowing it down this far.
