Yes, no need to replace cable
I had an ST50 system and went to ST60 because my ST50 boat speed display went bad. I replaced my displays first. So I had ST60 displays and ST50 trasnducers. It worked AOK with old cables. Then I looked at the ST60 wind transducer and figured as long as I have it (I bought the ST60 value pack- wind speed,depth) why not use the new one. It fit the old holder atop the mast. I also changed to a new ST 60 boat speed transducer. I just spliced it in using old cable.
With ST60 displays you have to splice them in since the connectors are different (and better). I kept the ST50 depth transducer. What I was told was that you could not splice this one in and that you had to use the cable attached to the transducer. I am lazy so I kept it.
I like the ST60 displays. Much nicer than the ST50's. If you can afford it make the change. If not and you need any ST50 parts send me a private email via this site. I have wind and boat speed transducers as well as depth, wind, and GPS displays. I have not had time to go through the process of listing on ebay.