So I found the resolution to this issue. After a strongly worded email to the parts manager and VP of the Thule group and some advice from a customer service rep, they are overnighting me an entire new mounting kit for the 2017 Chevy Silverado Track Rack sliding base rails. The shims, front stake blocks, rear stake adapter blocks, new square washers, new plugs, new nylon washers and new bolts. All for free. So anyone having this issue let me know and I’ll send you the email I sent and who I sent it to, to use as a template.