Like 16ACE27 said above, the easiest way to change the chassis battery is to go down through tl need to reinstall that wooden he top of the dashboard.
Remove all the screws holding the folding desk assembly and remove it like in the attached picture. You'll see a wooden piece partially cut out of the dash. Finish cutting this piece and remove it. You'll see the battery below the cutout.
After you change the battery you'll need to reinstall that wooden piece -- tape it, or use clips and screws, or whatever will hold the panel in place.
Ed & Bev Felker
Retired USAF Col and retired Nurse
Traveling with Lily & Bella ('Teddy Bear' breed)
2015 Vegas 24.1 (E-350)