better to buy a good used or rebuilt original one and take the Chevy emblem off and replace with repro GNC emblem - will fit correctly and look 1000 % , plus it doesn't lower the value of your truck come re-sale time . not many in So.Cal. came with heaters , I bought one from a fellow stovebolter for $50.00 .
The Trucj Shop in Orange , Ca. sells them and is having a 10 % sale towards then end of november - they're on Batavia .