Suspects that have both been at fault at one time or another in the past relating to battery drain, at least for me:

1)warning module next to cruise amp.(fried relay points) thru fuse #2.

2)anti-theft system module under passenger footwell (POS generally) thru fuse #15.

FWIW

__________________
The Golden Rule

1984 300SD (bought new, sold it in 1988, bought it back 13 yrs. later)