Farm Boy, I've done a fairly exhaustive search of my Chevrolet books and resource documents (shop manuals, parts books, dealer ads, GM Heritage documents, etc.) and can't find anywhere listing the original thickness of the flywheel for your truck. Most information I have read indicate it's safe to remove from 0.020" to 0.060" thickness from a most flywheels when resurfacing, but without knowing if yours has been resurfaced before, hard to say how much your shop can safely remove.
Perhaps there is another Bolter with knowledge of your flywheel dimensions that will chime in to try and answer your question?
