Chris Cooper is absolutely right. Most new digitiser replacements come without any soft foam padding on the connectors. These are sometimes essential for keeping the #3 connector down and steady. Keep your broken parts for these and other things like visual comparison. Ever had a good look at a 3G connector and a 3GS?
They are not really compatable. For instance do not use a iPhone battery number :APN 616-0435 into your 3G phone .It is for the Iphone 3GS only. Models for the 3G have lower numbers like 616-0364. They have chips which control them. The 3G is not the same as the 3GS so why expect them to work well with mutual batteries (sic). Beware of relabled batteries also. If you try to fix a 3G with a 3Gs batttery it will cause all kinds of problems...innability to sync with iTunes ect. On OFF low power, no power. Be careful out there. Sibo