I'm not an expert on this field, but below are some answers based on my knowledge.
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both(nam or modern) versions of m102 have airdrop rings?
Nope, only modern version. And "modern" is relative as M102's were phased out of service in 1990's.
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airdrop rings are removed in firing position?
No, AFAIK they were not.
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all m102s are painted in camo pattern?
Depends on the period. During Vietnam war they were olive drab, later they had MERDC camo pattern on them and then some of them were painted in NATO 3-color scheme.
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m102s in desert storm / shield ever poainted in sand ?
No, those I saw were still in camouflage pattern. And if I remember correctly I saw pictures of both MERDC and NATO camouflage on M102 in the desert.
Pawel