I just acquired a 6 GHz 8753C/85047A to replace my 3 GHz 8753C/85046A. I was going to swap the displays before selling the 3 GHz unit, because although the 6 GHz unit's display is ok, the one on the 3 GHz box is like brand new. The 6 GHz box was upgraded from a 3 GHz box (sticker on back indicating 11884A). I Googled on 11884A to try to figure out what the upgrade entails, and I'm wondering if it's just a software/firmware change. If it's just software, is there a way to upgrade my 3 GHz box so I don't have to change displays? Would Agilent let me get the upgrade out of one box and put it in another?