I have been trying to get a replacement digitizer for my daughters 2G Ipod touch that I dropped and broke. Apparently there are different part numbers that all seem to fit. I know the original part number is 821-0627-A but a lot of the replacements have different numbers like 821-0627-03 or 821-0627-04 or 821-0627-06. What is the difference between these replacement parts and which one is the best? I have been told that part 821-0627-A has been discontinued. HELP!!