https://www.hemmings.com/listing/1975-cadillac-eldorado-946202
I like the dk brown leather offered in 1975. The 50/50 front seats were a premium offering. The 1975 also has a few more horsepower than the 1976 version.
The small plastic monitor on the rear seat back of convertibles is a fiber optic to verify tail light operation. It's common to be broken, most cases they are completely missing. The 2 black 'wires' are the fiber optic cables and they cannot be spliced if cut or broken.
A handsome car! I think there is a guy who 3D prints and sells the "snake eyes" fiber optic holders and sells them on eBay- I got one and it looks good!