call gus - I've used these guys a few times - they don't always have what I need, but they are helpful and I've bought quite a few wheels from them.
http://www.originalwheels.com/chevro...els/trucks.php
And I concur with 67chevy1series - primary search is for a 71-87 K10 or K5 wheel (in case you ever stick disks on that front axle).