Universal Joint Replacement Guide for the 1979-1983 GMC P3500
Everything you need to know to replace the U-joints on your heavy-duty P-chassis van or motorhome.
- A clunking noise when shifting or a vibration at speed are the most common signs of a failing U-joint on a P3500.
- Physically inspect your truck to see if you have a one-piece or two-piece driveshaft, as you may need a center support bearing.
- You must measure your existing U-joints to confirm if you need a 1350 or 1410 series part before ordering.
- For heavy-duty use, Dana Spicer and Moog are highly recommended brands. Spicer is often the OEM-equivalent, while Moog offers excellent greaseable designs.
- Original factory U-joints may require a torch to melt out plastic retainers during the first replacement.
Signs of a Failing Universal Joint
A worn-out U-joint gives several warning signs. Because the P3500 is a heavy vehicle, these symptoms can appear suddenly and should be addressed immediately to avoid a dangerous failure where the driveshaft can separate from the vehicle.
- Clunking Noise: A loud "clunk" or ringing sound when you shift from drive to reverse is a classic sign of a bad U-joint. This is caused by excessive play in the joint's bearings.
- Vibration at Speed: A vibration that you can feel through the floor of the vehicle is another common symptom. This vibration often starts at a certain speed and gets worse as you go faster. It can sometimes be mistaken for an unbalanced tire.
- Squeaking Sound: A rhythmic squeaking that matches your driveshaft's rotation, usually heard at low speeds, means the U-joint is dry and has lost its grease.
- Visible Rust or Leaks: If you look under the truck, you might see rust-colored dust around the U-joint bearing caps. This is a sign that the needle bearings inside have turned to dust.
Choosing the Right Aftermarket U-Joint
For a heavy-duty vehicle like the P3500, choosing a quality U-joint is essential. The original parts were built to last, but modern aftermarket brands offer excellent quality, often with improvements over the original design. Here’s a breakdown of available brands:
Top Tier / OEM Supplier: Dana Spicer
Dana is a legendary name in drivetrains and was very likely the original equipment manufacturer (OEM) for your truck's U-joints. Spicer U-joints are known for their strength, durability, and precise fit. For a P3500 that hauls heavy loads, Spicer is a top choice for reliability and longevity. Many professionals and long-time GM truck owners recommend them above all others.
Premium Aftermarket: Moog
Moog is another highly-respected brand in the aftermarket world, known for its "Problem Solver" parts. Their U-joints are typically very strong, often featuring a greaseable design that allows you to flush out old grease and contaminants, potentially extending the part's life. This is a great feature for a work vehicle that sees hard use.
Reliable Aftermarket & OEM Brand: ACDelco
ACDelco is GM's official parts brand. You can trust their parts to meet OEM specifications for fit and performance. An ACDelco U-joint is a safe, reliable choice that will restore original performance without any guesswork.
Standard / Economy: GMB
GMB is a Japanese manufacturer that produces a wide range of quality automotive parts. Their U-joints are a cost-effective option that still provides reliable performance for daily driving and standard use. If you are on a tighter budget, GMB is a solid choice over no-name store brands.
Common Ordering Mistakes
Before ordering, you must confirm your truck's specific configuration. P3500 chassis were built for many different purposes, leading to variations.
- Not Measuring Your U-Joints: Your truck likely uses a heavy-duty 1350-series or an even heavier 1410-series U-joint. The only way to be sure is to measure the width of the joint and the diameter of the bearing caps. A 1350-series joint is about 3.625 inches wide, while a 1410-series is about 4.187 inches wide; both typically use a 1.188-inch cap. Ordering the wrong series will not work.
- Ignoring the Center Bearing: Check if your truck has a one-piece or two-piece driveshaft. If you see a rubber-mounted bearing holding the driveshaft to a crossmember about halfway down the frame, you have a two-piece shaft. This center support bearing should be inspected and likely replaced at the same time as the U-joints.
Estimated Replacement Costs
The cost to replace U-joints can vary based on how many need replacement and your local shop's labor rates. A P3500 can have two or three U-joints.
| Item | Estimated Cost |
|---|---|
| New Aftermarket U-Joint (Single) | $18 - $75 |
| Shop Labor (Per Joint) | $125 - $250 |
| Aftermarket Center Support Bearing | $40 - $120 |
| Total Per Joint (Professional) | $143 - $325 |
Cost estimates are approximate and can vary by location and specific parts chosen.
A Note on Installation
Replacing U-joints requires removing the driveshaft. Be sure to mark the driveshaft's orientation to the axle yoke before removal to maintain its balance. If your truck has its original factory U-joints, they are likely held in with injected plastic, not snap rings. This plastic must be melted out with a propane or MAPP gas torch before the old joint can be pressed out. New aftermarket joints will use snap rings for installation.
Frequently Asked Questions
How many U-joints does my 1979-1983 P3500 have?
It depends on the wheelbase. Shorter models typically have a one-piece driveshaft with two U-joints (one at the transmission, one at the rear axle). Longer models, like box trucks and motorhomes, often have a two-piece driveshaft with three U-joints and a center support bearing. You must inspect your vehicle to be sure.
Are greasable or non-greasable U-joints better for my truck?
Both have advantages. Non-greasable (sealed) joints, like those from Spicer, are very strong because the cross is solid steel and they are lubed for life. Greasable joints, like those from Moog, allow you to add fresh grease, which pushes out water and dirt, potentially extending their life with regular maintenance. For a heavy-use work truck, either is a good choice, but greasable joints require you to perform that maintenance.
What is a center support bearing?
On vehicles with long two-piece driveshafts, the center support bearing is a frame-mounted bearing that supports the middle of the driveshaft where the two pieces connect. It prevents the long shaft from whipping or vibrating. If this bearing fails, it can cause a rumbling noise or severe vibration. It's wise to replace it when you are replacing the U-joints on a two-piece shaft.
Can I replace a U-joint myself?
Yes, this is a DIY-feasible job if you have the right tools and are comfortable working under your vehicle. You will need a good set of sockets, jack stands, and either a bench vise with large sockets or a dedicated U-joint/ball joint press to remove the old joint and install the new one. If the original joints are in place, you will also need a torch to melt the plastic retainers.
Technical Specifications
OEM Part Numbers: 15633733
Common U-Joint Series: 1350, 1410. Retention Style: Outside Snap Rings (Aftermarket), Injected Plastic (Original OEM). Driveshaft Configurations: Single piece (2 U-Joints) or Two-Piece (3 U-Joints with Center Support Bearing).
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The information in this article is provided for general reference and educational purposes only. Vehicle specifications, procedures, and part compatibility can vary by production date, trim level, and region. Always consult your vehicle's factory service manual and verify part numbers before purchasing or performing repairs. Safety-critical components such as airbags, seat belts, and braking systems should be installed by a qualified professional.
- 🛍️ Shop This Part
- Signs of a Failing Universal Joint
- Choosing the Right Aftermarket U-Joint
- Top Tier / OEM Supplier: Dana Spicer
- Premium Aftermarket: Moog
- Reliable Aftermarket & OEM Brand: ACDelco
- Standard / Economy: GMB
- Common Ordering Mistakes
- Estimated Replacement Costs
- A Note on Installation
- Frequently Asked Questions
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