Try www.allhyundaiisuzuparts.com. E-Mail them a parts request and they'll get back to you in a day or two with a price.

You can also try calling some wrecking yards and asking them if they've got late model Isuzu's on the lot, and what vehicles the part cross references with. I've never had a problem getting compatible vehicle parts info that way - they've got to look it up anyway to see if they have the part you need. If they don't have it, they've got nothing to lose by telling you what vehicle you can get it from.

When you do find part numbers and cross reference information, please be sure to post the info here in case someone else needs the same parts in the future.