Guide to Universal Joint Replacement for the 1966 GMC I2500
Keep your classic GMC running smoothly by understanding the signs of a failing universal joint and how to choose the right replacement.
- Listen for clunking, squeaking, or vibrations, as these are the primary signs of a failing U-joint.
- For a 1966 vehicle, a new aftermarket U-joint from a brand like GMB is the most practical and reliable option.
- Inspect your truck to see if you have a one-piece or two-piece driveshaft to know how many U-joints to order.
- Do not ignore the symptoms; a complete U-joint failure can cause the driveshaft to detach, leaving you stranded and causing costly damage.
Symptoms of a Failing Universal Joint
A worn-out U-joint on your GMC I2500 will give you clear warning signs. Ignoring them can lead to a breakdown and more expensive repairs. If the U-joint breaks completely, the driveshaft can fall, leaving you stranded and potentially causing significant damage to the underside of your truck.
- Loud Clunking Noise: The most common sign is a sharp "clunk" or "bang" when you shift into Drive or Reverse. This is caused by slack in the worn joint.
- Squeaking or Chirping: A rhythmic squeak that changes with your speed, often heard at lower speeds, points to a dry, failing U-joint bearing.
- Vibration While Driving: You may feel a vibration through the floor of the truck that gets worse as you accelerate. This indicates an imbalanced driveshaft due to a bad U-joint.
- Visible Rust Dust: Sometimes, you can see a fine, orange rust dust around the U-joint bearing caps, which is a sign the internal needle bearings are failing.
Choosing the Right Aftermarket U-Joint
For a classic 1966 truck, finding new Original Equipment Manufacturer (OEM) parts is nearly impossible. The most practical and reliable solution is a new aftermarket U-joint. Aftermarket parts are made by companies other than the original manufacturer, and modern manufacturing often makes them a great choice for vintage vehicles.
GMB Universal Joints
GMB is a common aftermarket brand that produces universal joints for a wide range of vehicles, including older trucks like the GMC I2500. They are designed to meet or exceed original factory standards, using materials like cold-forged steel and heavy-duty needle bearings. While some online forum discussions from many years ago mention quality concerns, many recent user reviews find GMB parts to be a great value that fits and works well. For a standard-duty classic truck, a GMB U-joint is a cost-effective and reliable choice.
Estimated Costs for Universal Joint Replacement
The cost to replace a U-joint is reasonable, especially if you can do the work yourself. The main costs are the part itself and labor if you take it to a shop.
| Item | Estimated Cost |
|---|---|
| New Aftermarket U-Joint (GMB) | $18.53 - $23.80 |
| Shop Labor | $100 - $250 per joint |
| Total (DIY) | $18.53 - $23.80 |
| Total (Shop Repair) | $120 - $275+ |
Frequently Asked Questions (FAQ)
How many U-joints does my 1966 GMC I2500 have?
Most standard configurations have two U-joints on the main driveshaft. However, long-wheelbase models may have a two-piece driveshaft with three U-joints and a center support bearing. It is essential to inspect your truck to know for sure.
Is replacing a U-joint a difficult job?
It is a moderately difficult job that requires specific tools, like a heavy-duty vise, a ball joint press, or a specialized U-joint tool to press the old joint out and the new one in. If you don't have these tools, it's best to have a professional mechanic do the work.
Should I choose a U-joint with a grease fitting?
Yes. A U-joint with a grease fitting (zerk) allows you to add fresh grease periodically, which can extend its life. Non-greaseable joints are often stronger in design but cannot be serviced. For a classic truck, a serviceable joint is a good choice.
Are there any recalls for the 1966 GMC I2500 driveshaft?
No, there are no active recalls or technical service bulletins (TSBs) from the National Highway Traffic Safety Administration (NHTSA) for the driveshaft or U-joints on a 1966 GMC truck. Recalls on vehicles of this age are extremely rare.
Helpful Videos
Technical Specifications
The 1966 GMC I2500 uses external snap ring style U-joints. It is critical to measure your existing U-joint's cap diameter and overall width to confirm the correct size before ordering, as variations can exist.
We Have This Part in Stock
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.