CAT-TECH

I recently bought a 78 power wagon W-150 that was being used as a ranch truck. It runs and for having a burnt valve it pulls very well. I know that in the 80's Dodge had it's Lean Burn system but What did the late 70's run as in emissions equipment (since all smog equipment is missing)? Ive never dealt with the NP203 transfer case, only the NP205, was this case any good in being able to hold up to power?