Thumbnail sketch: No contact for 5 years = escheat. Used to be 7 years, was reduced a few years back. (Thanks to BOL for helping us stay on top of that!) "Contact" means account activity by the customer, correspondence, even cashing CD checks. However, our auditor, who used to work in this department for PA) says the screws are continually tightened over what is acceptable proof of contact.
Hope this points you in the right direction.