Actually, if you upgrade a 480 with the latest software I believe it will output Garmin's secret "ADSB+" format, which the 330S-ES can read, to get the needed data.
Another option: Buy the special Trig TT-22 from GRT. ($2200) It can read "ADSB+" from a garmin 480, 4xxW, or GTN series, or it can be fed from GRT's new $500 GPS box. It can be remote mounted and controlled thru a HX or HXr, etc. Not sure about the legacy boxes, but for about the same price you can just buy a regular TT-22 (you'd have to figure out how to feed the same encoder data from the GRT to the -22). (I think the new "mini" GRTs will drive it, too.)