Wheel Vintiques can build whatever you want checkout their measuring guide on there site
Here Get some cardboard, jack up your truck and start measuring, I spent a whole evening doing this on my truck before I ordered my rear's.
Ended up getting 15X8 Reversed one's and they came out great, I had a local shop Powerdercoat them for me.
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http://www.chevygmcofkc.org/Gallery/data/3021/1100_1221s.jpg[/img]
One note I've got a later model rear axle so 15X8's might not work for you, measure to be sure.
MONGO