inside NSgtdData.NOS you can find an item.dat that can be extracted with OneXExplorer.
u will get some informations like that
#================================================= =======
VNUM 2 400
NAME zts5e
INDEX 0 0 0 0 2 0
TYPE 0 1
FLAG 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
DATA 4 29 43 32 4 70 0 0 0 0 0 0 0 0 0 0 0 0 0 0
BUFF 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
LINEDESC 1
zts6e
END
#================================================= =======
in line 3 : INDEX [1]0 [2]0 [3]0 [4]0 [5]2 [6]0
The value [5] wich is 2 for this item is a reference to the item's icon in the inventory (stored inside NSipData.NOS)
EDIT : After re-reading your question i'm kinda in the wrong part of your answer. i've never been good manipulating morphs. But with some logic u can see that morphs values (if your item uses morphs) are the value [6] of the same line. Must share the same digits in morph-related files.