What specific problem do you have? The major grounds are located near the battery box on the frame.
On the links to Airstream manual I gave you in previous posts, you will find the schematics for the Airstream build.
This is specific to your 99 Cutter.
If its a Freightliner Chassis problem, you may contact your local dealer for access to the manual, of ask if they can download a copy of the specific page,problem and email it to you, if you are not close to the dealer.