Most diesels have gotten away from having to remove the shell, not so for many steamers.
The first three Legacy steamers I have in my manual folder all require you to remove the tender shell to install the battery.
Lionel 6-11117 Legacy Atlantic 4-4-2
Lionel 6-11156 Legacy C&O 4-6-0
Lionel 6-11327 Legacy K4 Pacific