I have a 332c and a 520c and want to network these two,just dont know how or what I need.

You should be able to get all the info you need off the Lowrance web site.

did the same thing. Changed the Console from LMS-332 to LCX-27. I continued to use the LGC-2000 (gps reciever) that was already there and got an adaptor cable to connect the new LCX-27 to the old LGC-2000.

Call Lowarance and talk about that, they can send that to you.

Also your next issue is to connect the two units together and share the LGC-2000.

See:
http://texasfishingforum.com/forums/ubbthreads.php/ubb/showflat/Number/1905919#Post1905919

There is two ways to connect/network the two units. I went with the simple and cheaper - just wire then togehter (NMEA-0183) versus the NMEA-2000 network cables approach.

Thanks !!