Can someone please tell me what setting I need use so I can sync our BB's with our Exchange GAL?

thanks in advance!

You don't sync the Exchange GAL to the device.
You use the Lookup feature of the device to Query the GAL on the fly when composing a message, or manually from the address book module.

Yikes! No kidding. Use the GAL lookup! RIM has made it very easy to use over the years.

Lookup feature is indeed very good. But we will not know who is calling, as the BB will not do an automatic lookup at the time of an incoming call. Hence the number only displays.
Solution for this is very crude...
Export the Global Address list (run a query on Active Directory), Import it to MS Outlook, Which will then soon initiate a sync with your BB handheld.
Unfortunately, this is a recurring process that needs to be done manually.

There's third-party software that will sync the GAL, but I still don't recommend it.