Does endurance over 10 increase HP gain per level?

More endurance means more HP, but would it help even more to equip dwellers with +endurance gear?

Solution 1:

Yes.

HP gains per level are based on the effective endurance stat, so +Endurance gear adds to this.

So to get the maximum health of 644 for a dweller, train them to 10 Endurance, and then equip them with the +7E Heavy Wasteland Gear.

Source: https://www.reddit.com/r/foshelter/comments/3ibkjj/endurance_affects_hp_only_during_leveling_not/

Additionally, looking at the game code:

healthMax += (CurrentLevel - lastLevelUpdated) * (EffectiveStat(ESpecialStat.Endurance) * HealthLevelModifierFactor + HealthLevelModifierBase);