Revell made a 1/32 OH-58A/C Kiowa. It is long out of production, but comes up on ebay quite often. There is one there now:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=50301&item=5957752383&rd=1&ssPageName=WDVW
It is a pretty descent kit, soft on exterior detail, interior is pretty good. Separate doors and left side fuselage cargo compartment door. Basic engine and transmission housing. Good fit. I have built a couple and highly recomend it.
Backdating a OH-58D to an A/C model would be quite a bit of work. You would have to reshape/rebuild the entire engine cowl are above the roofline. A lot of work. I would go with the Revell 1/32 model.
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