Has anyone tried flashing the new drive with their old & already patched firmware?
If the hardware's the same, you should in essence spoof your old drive, right?
If the drive continues to function (and you don't get banned), it should just be a matter of finding a correct way do dump the info you need, right?
This should rule out some possibilities..
(Note: I don't own a 360 myself, just sharing some thoughts)
You don't want to do that, unless you're sacrificing a machine for the good of the community. Repaired consoles get new keys, the old firmware may work, but the key won't.
I don't use JungleFlasher, I use DOSFLASH, FirmTool and my good ol' set of batch files, in Win98 command prompt mode, no Windows GUI loaded. I trust Windows to flash Hitachis but nothing else.
I doubt it was an 83850C, I'd have spotted that when looking for reasons why the serial was missing. I'll just put it down to repair-team laziness, and leave it blank rather than filling in from the labels.