Gt40 chirp or non chirp I have a buddy with one for a.chirp unit.
I dont think there is two different versions of the gt40.
I have a garmin 93sv (non-chirp and I called as well as looked at the site and it says the GT40-TM is compatible)
so if you have this one, I am interested. Can get on ebay $175-$200, checking to see if I can save a few bucks.