i currently have a gsd 22 on my 2530, hooked up to a 3206. it was installed in july and has a tendency to loose the bottom, and when it does it appears to lock up, but in fact if you change the range ( up or down) it will find the bottom again. once i figured this out it was a lot less annoying. this was a new and costly unit/install for me so i complained enough to have a garmin rep visit my boat and their position is that a gsd 22 will not work properly on my 2530 hull. Their remedy was to give me a transom mount transducer (which i have not installed yet).
i think i will install the new and keep the old one to have the "plug and play option"
hope this helps....
goog luck........