My '73 has a cluster from a European '83 99 in it, but swapping it was not so straight forward. Saab changed the resistance of the fuel gauge and sending unit in the tank, so when it originally went in, the fuel gauge would rise as I used gasoline.
I had to take both clusters apart and swap the guts so the gauge and sending unit would match.
Man, I wish Saab would not do that. Changing how the fuel gauge works is a real bummer for retrofitting newer parts! These days at least there are devices that can translate any sensor to any gauge... It's an extra cost, but it opens up options.