Since no-one pointed it out, the Mk1 Uno has the horn on the end of the single stalk (indicator switch) - has a nice solid feel, though you never use it. Well, I don't anyway
The Mk2 Uno has a more conventional rubber pad in the centre of the steering wheel.
The base model horn (behind the radiator grille) leaves a bit to be desired. Fortunately the 'S', 'SL', 'SX', and Turbo models, have the two windtone horns (snail-shaped) that should be bolted to the front rail under the radiator. Turbo models split the two horns apart - one in each front corner - except in mine that has been half-castrated due to the aftermarket air conditioning compressor location, so I have only a 'high' horn, a bit feeble!
The finest horn as far as I'm concerned was that fitted to the Lancia Thema series I ('86-'89). A wonderful 'gong-type' sound (in the words of the handbook), somehow achieved with standard-looking windtone horns through an electronic circuit. It sounded like a train!
I've never heard of anyone taking a horn off a Japanese car and fitting it to a FIAT as an *upgrade* - ah, but you did say aftermarket...
Dunc - so we both get by with only one horn, then! I've got the high, have you got the low?
-Alex