If by unit, do you mean Assoc? If so, Bay Metro Officials Assoc. located in Bay City, Mi. serving the Tri-Valley area (Midland/Saginaw/Bay City) may be of interest for you. We have about 300 registered and our website is
www.baymetroassoc.org. Down by Flint is the Genesee Officials Assoc.
You did not say where you will be living at, however you could stop in at mhsaa.com and look at the approved Assoc. within the state. Good luck!