The transmission year — the one third-gen Silverado where the 8-speed is the reason to walk unless it's been sorted.

The other expensive pattern. The 5.3L's cylinder-deactivation lifters can collapse, causing a tick, misfire, power loss, and often a bent pushrod and camshaft damage. Repair is $3,000–$10,000, and there's no recall — a class action alleges the defect while GM repairs reactively, so an out-of-warranty 2017 typically means owner-paid. Risk grows with mileage. An AFM disabler is cheap preventive insurance; a cold-start valvetrain tick is a warning to walk.

Some 5.3L and 6.2L trucks can develop a fuel-injector fault that makes the engine idle or run rough, stall, and throw a check-engine light. GM issued Special Coverage Adjustment N182198000 — but it only applies to vehicles in a specific list of emissions states (CA, CT, DE, ME, MD, MA, NJ, NY, OR, PA, RI, VT, WA). If the truck was sold or registered in one of those states, the injector repair may be covered; elsewhere it's owner-paid. Confirm eligibility by VIN.

On trucks with the power sliding rear window, GM documented "areas of high electrical resistance on the rear defroster circuit," caused partly by the mechanical stress of opening and closing the window, debris getting in, and use of the defroster. GM's own wording is that over time the heat "could melt the areas surrounding the circuit" and, in rare instances, "cause a non-propagating fire." The Customer Satisfaction Program covers the buss bar and contact covers, and the glass itself where it has already been damaged. The program's stated scope runs 2014 through 2019, so this year sits inside it. Establish whether the truck has the power sliding window, run the defroster and cycle the window through its full travel while watching for anything that smells hot, and check the program by VIN.

Like the rest of the third generation, the 2017's A/C condenser can crack and leak with no recall behind it, running about $1,000 out of pocket; compressors fail too. Run the A/C cold on a warm day, and look for the upgraded-condenser mark in the top-right corner as a sign it's already been replaced.

The mechanical vacuum pump behind the brake booster can lose output over time, giving a hard pedal and longer stops — covered by recall 19V645 and a related GM Special Coverage for 2014/2017/2018 trucks. A firm pedal and a 'Service brake assist' message are the tells; verify by VIN the recall/coverage work was done.