Thank you for your post.
I assume when you said "I have 4 iPads one of them I had when they first came out", you actually mean after the iPads with 3g first came out. Assuming that is the case, I would look at the settings between the working 3g iPad and a non-working 3g iPad and see what are the differences. Naturally, make sure the working iPad is indeed using 3g and not Wi-Fi syncing. If you discover that you are using Wi-Fi on the first iPad, then make sure port 5003 is configured for port forwarding.
Please keep me updated with any progress.