"chunk" does not mean anything when it comes to vehicles. Cheese or chocolate maybe, but not trucks.
If you are talking about the read axle then I would check ebay or go to your local pull-it-yourself junkyard. GM 10-bolts are very common GM vehicles. Aother option is checking out govliquidation as they are selling off many of these axles. I bought two new in the crate for $50 each two weeks ago. Recently they are being sold out of the Norfolk, Va. location. They still have a couple left from abandoned lots and such. Shipping would be your only real cost.