Hit dice for monsters in both editions of AD&D are almost always d8s, so it's normal for monster stats to say things like “6 HD”, “3 HD + 4”, or “½ HD” with no further explanation given.
From the Monster Manual introduction where how to read statistics is explained:
HIT DICE indicates the parameters of the number of hit points a creature can withstand before being killed. Unless stated otherwise, hit dice are 8-sided (1–8 hit points).
Most monster stats only list HD, since that's sufficient to determine hit points (and economical of page count). Actual hit points are rarely listed except when an adventure indicates how many a specific individual creatures has, and even then it’s common to list only HD, with HP to be determined when needed.
If you come across any HD stats with a plus, that's covered in the same passage, where it explains that it's added once to the sum of the dice.
Although AD&D does have a deserved reputation for being poorly organised, the books are fairly reliable at explaining core concepts like this. When in doubt about monsters, consult the Monster Manual and you'll be good.
Aside, that “AC 14” is ascending Armour Class which will have to be converted to descending AC (lower is better) to work in AD&D’s rules — assuming you're not using ascending AC house rules. To convert ascending AC to AD&D’s descending AC, just subtract it from 20; in this case 20 − 14 is 6, for a descending AC 6.