Will,
Since I didn't say before, Welcome to the forum!
Sorry I can't help with the wiper... Usually you can re-use the arm (the part that actually fastens to the motor) and you should be able to find replacement blade carriers in the bigger automotive shops (Halfords) - it's just a shorter size than the front. My Uno's rear wiper is 335mm (I just checked) which is about 13-14". There are two main styles of clip for holding the blade carrier to the arm: a hook type, or one that slides onto the flat part of the arm having a bump to locate it (mine has the latter). Replacements usually fit both types. Maybe if you get really stuck, try looking at older cars in scrapyards. Cars of the 70s typically had short wiper bladers (though, I suppose those cars are all gone now.)
Now how about those other problems...
- The new engine?
- The fuel tank with a leak, you should be able to find a 2nd-hand replacement easily enough, maybe ring a specialist FIAT breaker (look up FIAT in the yellow pages under Parts, etc.) As far as I know, the fuel tank is not a common failure.
- CD player, try taking the lid off and cleaning the lens with a cotton bud dipped in isopropyl alcohol (or maybe glass cleaner), or if it's skipping badly try making the mounting tighter. Pieces of thin carpet or foam tend to help, and a strap at the back screwed to the heater casings. If neither of these things work, just splash out on another MP3-playing CD headunit (only about 70 pounds these days?) and sell on eBay the one you've got.
Driver's window - is it electric? I'm guessing not (I think far more Unos over here had electric windows than in the UK) so it's easy to swap out the regulator (and maybe another item to ask for at the same time as the fuel tank. Again, I don't think the manual window regulators are a common fault (I've got a couple of spares, and my Uno has electric windows!)
Electrics of course can be a lot more exciting and challenging...
-Alex
