The search often comes from vehicle enthusiasts who despise the current "everything is a monster" approach. The PDF is a treasure trove of proper tank rules.
Do you need help finding that still play retro editions of 40k?
The 6th Edition codex integrated background and lore more closely with rules and unit presentation. Detachment bonuses, chapter-specific traits, and named characters were better aligned with the Space Marines’ heroic, martial image. This helped hobbyists and players who wanted their forces to reflect specific chapters or narrative concepts without sacrificing competitiveness.