Wow. For those of you that don't want to read the details below, here are the highlights from my experience with GSP Axles from Advance Autoparts:

-1 axle failed after 0 miles (outer joint assembled wrong, so it fell apart as I was installing the axle)
-Outer boot on other axle started leaking on initial test drive
-Inner joint came completely apart after about 3000 miles.

The low price and "lifetime guarantee" are very attractive, but there seem to be very, very serious quality control problems with these axles.

Now for the full story:

When I purchsed the 84 300D the boots on both CV axles were torn, so I went ahead and purchased two new GSP axles from Advance Autoparts a few months ago. Left axle installed fine, after removing the spacer ring. The right axle was a bit more trouble, since it required me grinding the inside of the spacer ring a bit so that it would sit flush with the new axle. After installing the right axle I gave the tire a spin to make sure everything felt right and just heard a "clunk, clunk, clunk." The outer joint had separated. I got the axle off and cut into the boot. The C-clip on the outer joint has never been installed, so the joint just fell apart as I bolted the axle to the hub.

I had AA order a free replacement. This took a full week due to some unfortunate screw-ups, but eventually I got the new axle, which installed without issue.

Since then, my wife and I have driven the car about 3000 miles, including a 1200 mile round trip to FL (this trip to FL was the main motivation for replacing the axles in the first place, since I didn't know the condition of the old axles with the torn boots and didn't want an axle failing while cruising down I-75.) Today, my wife was driving down the road back to our house (55 mph country road, but with a decent amount of traffic) when she heard a rapid thump, thump, thump. She was about to turn into our neighborhood, and was only half a mile from the house, so went ahead and kept going. Once in the neighborhood, she was heading up a hill when she went over a speedbump and the car suddenly would't drive. Moreover, putting it in park had no effect.

So my wife (who is physically handicapped, by the way), is stuck in the middle of the road on this hill with a car that won't go forward and won't go into park. She put it in neutral and drifted down the hill a
bit and got the car off of the road and into someone's yard. She then hobbled home.

I found a ride home from work (my wife had driven me in this morning) and crawled up under the car. The inner joint on the left axle had come completely unbolted (I suspect the bolts came loose when she was going 55, resulting in the "thump, thump, thump", then going over the speedbump pulled the axle completely apart), and the axle was sitting on top of the exhaust (I'll post pictures later). All of the bolts were there, so I bolted the joint back together and drove the car the 100 yards back to the garage. I'm ordering rebuilt axles from CVJaxles this afternoon. I'll see if AA will let me return the axles for a refund.

So, the moral of the story: No matter how attractive the price is on these GSP axles, please, please just bite the bullet and buy quality rebuilt axles. Luckily, this axle waited until my wife was going 25 mph through the neighborhood to completely fail, rather than failing while going 55 with some fool tailgating her.

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84 300D 255K "Mr B" ("Mr Becker")
79 300D 265K "Mrs B"
85 300TD 175K "Mali" (Sold)
74 Ford F-100 74K "Bonnie" (Sold)
67 Jeepster Commando (Sold)