Types of Armor and Encumbrance
Gary lists types of armor, including shields, along with how "bulky" they are (he doesn't explain what significance that has in this section, though a note on shields later on implies that it has something to do with encumbrance separate from weight), their weight (adjusted to take into account weight distribution and the armor's effect on mobility), the base movement rate of an individual wearing the armor and short explanations of each type of armor. Both price and AC are missing; I suspect that AC will probably be in another section of the DMG, but a quick skim of the combat section didn't turn anything up.
More interesting are the notes Gary follows this list up with. For example, if PCs don't wear helmets, 1/6 attacks against him are aimed for his AC 10 head; if the opponent is intelligent, then it's every 1/2. There was some discussion a few years back in the OSR about helmets, but I don't remember that harsh consequence for not wearing a helmet ever come up; on the one hand it makes great sense but on the other hand it's both very harsh, especially to characters who can't wear helmets, and it calls for an extra die roll for every attack against helmet-ed PCs.
Shields are only allowed to improve AC against the front and the left. Gary justifies large and small shields providing the same abstract amount of mechanical benefit because, while large shields protect more area at one time, they also cannot be moved around as easily as small shields and they fatigue the user. Gary does allow for an optional rule: large shields provide a +2 bonus against projectiles, instead of the standard +1.
Dexterity and Armor Class Bonus
Gary explains that any penalties to dexterity from wearing armor are already taken into account, so a high Dexterity always provides a bonus to AC…
Except for attacks from behind that the character can't see coming, large (siege weapon style) projectiles and certain magical attacks.
Weapon Types, "To Hit" Adjustment Note
Gary points out that the optional bonuses to weapons against certain types of armor are against certain types of armor and not against the armor classes themselves; that is, if a weapon is +1 against an armor with AC 7, the armor isn't +1 against a monster not wearing any armor but with a natural AC of 7. By the same token, the DM may give that weapon a +1 bonus against another monster with a natural AC of 5 which has natural armor resembling the type of armor the weapon gets a +1 bonus against.