What is the GMC puck system?

It's GMC's factory Gooseneck/5th Wheel Prep Package on the Sierra 2500HD and 3500HD. It puts a five-hole puck system in the bed — four corner pucks for a fifth wheel hitch plus a center hole for a gooseneck ball — so compatible hitches drop straight in without drilling. GMC identifies it with RPO code Z6A.

Which GMC Sierra trucks have the puck system?

The Sierra 2500HD and 3500HD, from roughly 2016 on, across trims from Pro and SLE up to SLT, AT4, and Denali. It's an optional package (RPO Z6A), not standard equipment — so verify your specific truck. The half-ton Sierra 1500 does not offer the factory puck system.

How do I install a gooseneck hitch on a GMC puck system?

A gooseneck hookup on the puck system uses three of the five holes. Drop the OE gooseneck ball into the center hole and turn it a quarter-turn to lock. Then drop the two safety-chain anchors into the two rear pucks (the pair nearest the tailgate — they only fit there). No drilling and no tools required. The gooseneck ball and anchors are often sold as a kit separate from the prep package.

How do I know if my Sierra has the pucks?

Open the glovebox and check the RPO code label for Z6A — that's how GMC flags the prep. Or look in the front half of the bed for five capped holes (four in a rectangle plus a center hole); if there's a bed liner, pull it back or check for the molded cutouts first. For certainty, give a GMC dealer your VIN and have them read the build sheet.

Will a 2016-2019 Sierra fifth wheel hitch fit a 2020 or newer Sierra?

The gooseneck ball carries over, but the fifth wheel hitch legs do not. GMC redesigned the Sierra HD for 2020 and moved the puck spacing, so puck-mount fifth wheel legs are year-specific: 2016-2019 won't fit 2020+, and vice versa. Match the hitch to your exact year.

GMC Puck System

Q: What fifth wheel hitches fit GMC pucks?

Any 4-point fifth wheel hitch built for the GM OE puck system drops into the four corner pucks — the B&W Companion OEM (GM version), CURT Q-Series with puck legs, and PullRite OE are common picks. For a gooseneck-ball setup instead, add a gooseneck ball plus a gooseneck adapter pin box for a single-point fifth wheel hitch. Confirm year-specific fitment before buying.

Written by a towing industry expert Updated July 2026

The short answer: GMC's Sierra HD puck prep (RPO Z6A) is a 5-hole system — how to spot it, how to hook up a gooseneck, and what fifth wheel hitches fit.

What Is GMC's Puck System?

On the Sierra HD, GMC's factory Gooseneck/5th Wheel Prep Package is a five-hole puck system built into the bed — four corner pucks for a fifth wheel hitch and a center hole for a gooseneck ball. Everything drops in and quarter-turns to lock. No drilling, no rails, and a flat bed the moment you pull the hitch.

Which Sierra Trucks Have It?

HD only — ordered as an option

Sierra 2500HD

2016 and up

Sierra 3500HD

2016 and up

Because it's an ordered option, you'll see it on everything from a base Pro or SLE work truck up through SLT, AT4, and Denali. The half-ton Sierra 1500 doesn't offer it.

Important

The prep is an optional package (RPO Z6A) — not every Sierra HD has it. A loaded Denali can lack it and a stripped Pro can have it. Check before you buy a hitch.

Installing a Gooseneck on the Sierra Puck System

Three holes, no tools

This is the one people search for most, and it's genuinely simple. A gooseneck hookup uses three of the five holes:

1. Drop the OE gooseneck ball into the center hole and turn it a quarter-turn to lock.
2. Drop the two safety-chain anchors into the two rear pucks (the pair nearest the tailgate — the anchors only fit there).
3. Hook up, chain up, and go. Pull it all back out when you're done for a flat bed.

The gooseneck ball and safety-chain anchor kit is usually sold separately from the prep package — check for a padded case in the cab before buying one.

Watch the Year: 2016–2019 vs. 2020+

Fifth wheel legs are year-specific

GMC has offered the puck prep since 2016, but the Sierra HD was redesigned for 2020 and GM shifted the puck spacing.

The gotcha

A gooseneck ball swaps freely between the generations, but a puck-mount fifth wheel hitch's legs are year-specific — a 2016–2019 leg set won't bolt into a 2020+ Sierra HD. Always match the hitch to your exact model year.

What Fifth Wheel Hitches Fit GMC Pucks?

Two ways to connect

4-point fifth wheel hitch

The standard rig — four legs lock into the four corner pucks. Look at the B&W Companion OEM (GM version), CURT Q-Series with puck legs, or PullRite OE. Confirm year-specific fitment first.

Single-point fifth wheel hitch

A single-point fifth wheel hitch (like the PullRite 3900) mounts to one central point on the gooseneck ball instead of the four corner pucks, and grabs your trailer's kingpin normally. (A gooseneck pin box such as a Reese Goose Box also tows a fifth wheel off a ball, but it's a trailer-side pin box, not a hitch.)

Which one fits your GMC?

Enter your year, make, model, and bed — we'll show only the hitches that actually bolt on.

See GMC Hitches

Want a shortlist instead? See the best puck-mount fifth wheel hitches, or how to install one.

What About the MultiPro Tailgate?

Nice feature, not a fitment factor

The Sierra's available MultiPro six-function tailgate is a great cargo tool, but it doesn't affect the puck system or which hitch fits. The real towing question is bed length — a full 8' bed clears a fifth wheel easily, while a shorter 6.9' bed can bind on tight turns. Fix it with a slider hitch, a hitch with a built-in offset, or an offset gooseneck ball plus a gooseneck pin box. See Short Bed Towing for the details.

What If My Sierra Doesn't Have Pucks?

Aftermarket has you covered

The factory prep can't be retrofitted (it's welded in during assembly), but you can add an aftermarket mount and tow without issue:

ISR Rails

Industry-standard rails bolt in and accept any 4-point rail-mount fifth wheel hitch.

Under-Bed Kit

A Turnoverball-style gooseneck kit adds a single center ball for a single-point setup.

Weighing the options? Start with Rails vs. Pucks. And since the Sierra and Silverado are mechanically identical, the Chevy puck guide and the GM overview apply to your truck too.