If anyone is interested, here is a list of Oakland County's outdoor warning sirens. They have a mixture of 1003ATs, SD-10s, and 2001s. Currently, the game plan is to start replacing as many Thunderbolts as possible, with annually allocated funds, which will be used to purchase mechanical replacement units. Likewise, each siren is be fitted with a two-way monitoring system that will be used to check the status of each unit. In the past, Ham Radio Operators were used to drive out, and physically check each siren to confirm if it was operating properly every month.
http://www.oakgov.com/erp/assets/docs/s ... n_list.pdf