The smallest complaint file in the band — and the most expensive individual failures in it.

The transmission dominates this year's small file and the reports are consistent. One owner lost drive at 93,000 miles and was told the VIN was not included in campaign 24V797. Another was quoted $7,000 at 100,000 miles by a transmission shop that said it sees one or two of these weekly and that 2016–2020 Chevrolet transmissions "are no good." A third paid $2,200 for a torque converter that did not cure a severe shudder. A fourth found metal pieces in the transmission after it quit at 70 mph. Several stress that no warning light came on first. There is no recall and no special coverage on a 2020 gas truck. Drive it until the transmission is hot, feel every shift, and pull the dipstick.

AFM — Active Fuel Management, the system that shuts off cylinders under light load to save fuel — uses collapsible lifters that can stick or collapse and scar the camshaft. In this year's file that is not theoretical: one owner was told the cylinder lifters had collapsed and the crankshaft was broken, with a quoted repair of $10,000 to $20,000; another needed a camshaft at 95,000 miles; a third had a 6.2L RST on its third engine at 70,000 miles. One owner cites GM's own service bulletin 19-NA-218 for lifter and push-rod failure — a TSB is a Technical Service Bulletin, the fix instructions an automaker sends dealers, not a recall and not free. Cold-start and listen before anything else.

A recurring thread in this year's file is electrical rather than mechanical: instrument clusters going black, wipers and power steering cutting out and restoring themselves, a truck that stalled and would not restart until cables were pushed back into place. One owner reports a dealer citing Technical Service Bulletin 18-NA-161 for the condition and argues it should have been a recall given what it affects. Another describes a wiring harness that has failed repeatedly, each time costing power steering while driving. On the test-drive, watch the cluster and the power-steering message centre, and scan for stored codes even with no light showing.

Two owners in a 40-complaint file report the water pump letting go — one at 30,000 miles with a banging noise from the engine bay and the gauges and air conditioning misbehaving, another bursting without any warning at all. In a file this small that is a noticeable share. It is a routine repair by the standards of everything else on this page, but worth a look at the coolant condition and any weeping at the pump when the truck is on a lift.