The GM Gooseneck Prep Package
The short answer: Prep means the structure, not the hitch. Five capped holes and no gooseneck ball is exactly what the package is supposed to look like.
In This Guide
The 2-Minute Answer
GM's Gooseneck/5th Wheel Prep Package is exactly what the word "prep" says it is. You get the structure, the holes and the wiring — you do not get a gooseneck ball, and you do not get the safety chain loops.
That single sentence resolves most of the confusion around this option. Owners buy a truck the dealer described as "gooseneck ready," drop the tailgate expecting to find a ball, and see five plastic caps instead. Nothing is missing. The ball was always a separate purchase.
The good news: the expensive, non-retrofittable part is the part you already have.
What the Prep Package Actually Includes
Three things, all of them structural
The under-bed platform
A heavy steel frame welded to the truck's frame rails during assembly, with a tray that accepts a gooseneck ball. This is the part that carries the load, and the part that can't be added later.
Five capped holes
Cut in the bed floor at the factory and finished with removable caps. Four in a rectangle for a fifth wheel hitch, one in the center for the gooseneck ball.
An in-bed 7-way plug
A trailer connector mounted inside the bed, normally on the driver's side wall near the front, so your trailer cord doesn't have to run the length of the truck.
That's the package. Notice what all three have in common: they're things that have to happen while the truck is being built. GM sells you the part you can't add yourself and leaves the bolt-on hardware to you.
What It Doesn't Include
The part that surprises people
No ball, no chain loops
The 2-5/16" gooseneck ball and the two safety chain loops come from a separate hitch kit. GM sells one as a dealer-installed accessory — it shows up as its own line on the window sticker, not bundled into the prep package — and the aftermarket sells several.
If you're standing in a prepped bed with nowhere to hook a safety chain, that's not a fault. The loops drop in with the ball.
Worth knowing if you're towing a fifth wheel rather than a gooseneck: you don't need any of it. A fifth wheel hitch bolts to the four corner pucks and grabs the trailer's kingpin. The center hole stays capped, and fifth wheel connections don't use safety chains. The ball kit only matters if there's a gooseneck coupler in your future.
How to Tell If Your Truck Has It
Three checks, in the order that costs you the least time
- 1. Look in the bed. Five capped holes in the front half of the floor — four in a rectangle, one in the middle. A properly sprayed bed liner goes around them, so they should be in plain sight.
- 2. Look for the in-bed 7-way. Every factory puck installation includes one. No plug inside the bed is strong evidence the truck was never prepped. It doesn't work in reverse, though — a 7-way can be added aftermarket or come with a different tow package.
- 3. Check the RPO label. Open the glovebox and find the silver sticker of three-character codes. Z6A is the prep package. On 2020 and newer trucks some trims carry it inside a bundled package code instead, so a missing Z6A on a newer truck isn't proof of anything on its own.
When those three disagree — and on used trucks they sometimes do — hand any Chevy or GMC dealer your VIN and ask them to read the build sheet. It takes them a minute and it costs nothing.
Can't find the caps?
A bad liner job is the usual culprit. Finding Your Prep Package Under a Bed Liner walks through telling that apart from never having had it.
Want the full checklist?
Does My Truck Have the Prep Package? covers Ford and Ram too, including what each brand calls it on the sticker.
Do You Have to Use GM's Ball?
No, and you often shouldn't
The factory kit works fine. It is not, however, your only option, and it isn't usually the strongest one. Any ball kit built for the GM puck pattern drops into the same hole and latches into the same tray — the pattern is what has to match, not the badge on the box.
B&W, CURT, Reese and PullRite all make one. Several are rated well above the factory kit, and some of them fit the Ford and Nissan puck patterns too, so the kit keeps its value if your next truck isn't a GM.
One thing to check before you buy
Ball kits are rated by gross trailer weight, and the ratings vary a lot between them. Match the kit to your trailer, not to your truck — a 30,000 lb kit on a truck rated for 20,000 lb is wasted money, and the reverse is dangerous.
There's a second, quieter reason people replace the factory ball: the aftermarket kits generally handle stowing better. Everything drops out and the bed goes flat again, which is the whole point of a puck system.
Three Kits That Drop Into GM Pucks
All three are ball plus safety chain loops, all rated 30,000 lb
These are complete kits, not just a ball — the chain loops come with them, which is the part people forget they need until they're hooking up.
B&W OEM Gooseneck Ball & Safety Chain Kit — GM/Ford/Nissan Puck
Part GNXA2061 · 30K gross trailer weight · 2016–2026 GM
Spans the 2020 spacing change, so it fits either generation. Also fits Ford Super Duty 2017+ and the Nissan Titan XD.
Specs, fitment and where to buy
OE Gooseneck Ball & Plate
Part 4437 · 30K gross trailer weight · 2016–present GM
The widest coverage of the three — Ford back to 2011 and Ram back to 2013 as well, so it keeps its value if your next truck isn't a GM.
Specs, fitment and where to buy
Curt OEM Puck-System Gooseneck Ball (30K)
Part 60629 · 30K gross trailer weight · 2020–2026 GM only
Fitted to the post-2020 GM beds here, not the 2016–2019 trucks. Check your year before ordering this one.
Specs, fitment and where to buyAlready have a ball and only need somewhere to hook the chains? The safety chain anchors are sold on their own too — you don't have to buy the whole kit twice.
If You Don't Have It
Still perfectly towable
The factory prep can't be added after the fact — that platform is welded in while the truck is on the line. But this is a solved problem, and the solution is not a compromise.
For gooseneck
An under-bed gooseneck kit bolts to the frame and gives you the same flip-over or drop-in ball in the middle of the bed. B&W's Turnoverball and CURT's Double Lock are the two you'll see most.
For fifth wheel
A rail kit does the same job for a fifth wheel hitch. Rails vs. Pucks covers what you give up and what you don't.
The 2020 Gotcha
Applies to the hitch, not the ball
GM redesigned the HD trucks for 2020 and moved the puck spacing. Fifth wheel hitch legs are therefore year-specific: a set cut for 2016–2019 won't fit a 2020-or-newer bed, and vice versa.
The center gooseneck hole came through the redesign in better shape, so several ball kits — the B&W and PullRite above among them — cover both generations. Not all of them do, though, so read the year coverage rather than assuming. If you're shopping for a fifth wheel hitch, match it to your exact year without exception. Puck System Dimensions has the numbers.
Related Guides
The Chevy Silverado HD and GMC Sierra HD share the same puck system. The quick overview (RPO Z6A, the 2020 change), then jump to the Chevy or GMC guide.
Read guide →The 2-minute way to tell if your Ford, Ram, or GM has the factory fifth wheel/gooseneck puck system.
Read guide →Ford, Ram, and GM puck patterns by year — what interchanges, what doesn't, and which hitch matches your truck.
Read guide →