Fish finder power plug compatibility.

[fishnut]

The newer sounder technology is generally miles ahead of the older stuff. i highly doubt your old transducer will be compatible with the newer units, all depends on what model you get ofcourse.
my 2c. rip it out and use the new one that comes with the new unit

As purple said,also im pretty sure the new units come with shielded cables so i would use all the new ones,besides not a big or difficult job to change the power cable