Here is a bit of information that comes from professional experience. It is the sort of stuff that may go entirely unnoticed by the average car owner who can only wonder why replacement universal joints do not last as long as one might expect. But it does arrive at a recommendation on which U-joints to buy and which ones you may want to avoid.

On November 6, 2018, Tom Yearnshaw wrote:
"Last year, I found the driveline U-Joint at my rear differential to show very slight movement. I was replacing the differential input seal anyway and decided to pull the driveline for a thorough inspection. Since I wanted to get the car on the road again, I first shopped locally for U-Joints, and what I found was VERY DISTURBING.

First, a little background - and I am not trying to toot my own horn - just explaining. In addition to doing my own maintenance on this MGA for 40 plus years, I worked for twelve years as a mechanic for a fleet of trucks (20 truck-trailer combos averaging about 100K miles per year) [That would account for 24 million miles of truck travel]. Without boring you with a bunch of details, I inspected and/or replaced thousands of U-Joints, wheel bearings, transmission and differential bearings, and a whole bunch of other wear parts. I also have a degree in mechanical engineering, where metallurgy was not my specialty but was a study requirement and where I have hands on experience in that field. My big mistake 25 yeas ago was to not purchase a lifetime supply of Spicer U-Joints for the MGA!!! HA!!! I eventually simply purchased the GNK U-Joints from Moss but also (carefully) picked up some vintage Spicer over the last year from eBay to have on hand in case of an emergency.

Locally, I purchased three pairs of U-Joints and then returned all three after close inspection. Two "brands" - NAPA's top tier (in stock locally) and the top quality selection at O'Reilly Auto Parts (overnight special order) - were identical except for the packaging. The third, boxed as "NEAPCO" and available at an auto parts store in Reno, was distinctly different in appearance and apparently came from a different source. All three, though, were of the same poor quality, and all three were junk. I wasn't in such a pinch that I had to install any of these. I rejected all three and ordered from Moss. In an emergency, any of the three would last safely but would not be my long term maintenance solution.

Here is what I found unacceptable on all three local sample pairs: First, under a 50X magnifying glass, all three showed significant areas of large "flakes" of soft material in the metallurgy of their crosses. That was pretty disturbing. Using a sharp pick, I could actually flick off metal !!! Second, again under the 50X glass, the rollers in the cups from all three samples were of the same poor material and finish as the crosses. Again, very disturbing.

Finally, all three local samples showed significant "dings" on all four crosses. I suspect that those dings occur because the finished crosses fly into piles (think plastic totes or 55 Gallon drums) off a conveyor belt and are allowed to damage each other as they hit the pile. We would not handle U-Joints in such a way after purchase. That a manufacturer would do so implies poor quality control.

By comparison, while the GNK joints from Moss and the vintage Spicer joints I purchased from eBay do show ran minor imperfections under the strong glass, they are a quantum leap in quality above the other three.

I stopped working full time on trucks in 1999, but from 2000 through 2006, worked as a test engineer at a facility that tests all manner of moving machinery from large military vehicles to riding lawn mowers. You've probably had similar experiences to mine, but from the time I started working on vehicles in the early 1970s through my early years as a mechanic in the late 1980s, high quality vehicle parts were common. During the later 1980s and the 1990s, the whole supply chain for all manner of vehicle parts became more and more consolidated into large conglomerates, and as this transition occurred, parts quality deteriorated as competition decreased. We who love our vintage cars can sometimes really come into a pinch. Moss does a fairly good job of quality control, but I have occasionally bought parts from them that are also not acceptable. They are limited by the same supply chain changes that disrupt us all.

Well, Barney... I am sure you are subjected to supply problems as you travel, so I am preaching to the choir. However, I did want to provide some insight into my experiences with the U-Joints. I don't expect much from O'Reilly but was especially disappointed in the NAPA U-Joints. Historically, I do not buy much from NAPA, as they are really high priced, but also historically, when I need a good quality part, they were a place to trust. I took my glass with me when I returned their U-Joints and had the local manager take a look. He was shocked at the poor quality". -- Tom

U-joints judged to be poor quality:
NAPA's top tier and the top quality selection at O'Reilly Auto Parts.
"NEAPCO" available at an auto parts store in Reno.

U-joints judged to be good quality:
GNK joints from Moss.
Spicer joints (vintage parts) purchased from eBay.

Here are a few more notes on pior encounters of other problems with Universal joints:

MG steering U-joint snap rings do not fit - This has been fixed, but there may still be some of the prior problem parts remaining in stock.

There was also a case somewhere around 2010 time frame when replacement propshaft U-joints (from Moss Motors in this case) could not be installed because the spider was too wide across the bearing caps, so the snap rings could not be installed. The dimension error was ony a few thousandths of an inch, so this could be "fixed" in a pinch by sanding the snap rings to be a bit thinner. This part was subsequently discontinued (by Moss Motors) in favor af a better part.