If it were me, I'm not sure that I would buy a used unit unless I was going to install it right away, or unless, the seller is willing to give you some kind of warranty. I'm not trying to stop a sell from anyone here on THT, but if you buy it ,and then 30 to 60 days later go to install it to find out is does not work or you don't have all the correct parts to install it then what are you going to do with a unit that is not working for you or you have to buy parts that will make you wish you had bought a new one. Not a tough call for me for something you can see that it works before you buy it. Also, make sure your transducer will work with the GSD unit you are buying..
I give Gill


So check with him on what all you will need. I just bought a unit from him...Quick shipping and easy to work with. Just make sure someone can be at home to sign for it or send it to your work place..(signature required by Gill)