Actually Battle Dress is listed in at least the 1981 LBB1 version, page 42. It does not explicitly say to use Combat Armor modifiers, but it does say BD is a powered version of CA. Since those CA mods are the best, it's logical to extrapolate those are the ones you use.
The notation in LBB4 weapons/armor mods, page 51, is for Battle instead of CA so that should be clear enough.
What is introduced in LBB4 is Battle Dress skill (before you would just use Vacc Suit skill), and the BFGs of the Traveller world, the PGMP and FGMP weapons that require BD.