"Aftermarket" driveline on Tacoma with 30,000 miles??

Yeah I screwed up and I've been told! Trying to get someone to swap out the thread but it hasn't happened. The information obtained has been most valuable in any case!

 

San Francisco Bay area! While the shop was apparently very confused, they weren't being dishonest. They went out with me for a test ride, put the truck on the rack and had it for most of the day dealing with Toyota.They didn't charge me a dime. Apparently the Toyota parts department was part of the problem as well, having told them it was an aftermarket shaft.
I'm scheduled to bring it to another shop Monday. I should have this resolved next week, and I plan to go back and talk to the first shop, to enlighten them with what I've learned here.
I'll report how that goes.

 

The shop I'm going to on Monday said it should take about an hour. He said that there is a possibility that they'll break the stem (I think that's what he called it), implying that would complicate things. He said it's rare but it can happen. I didn't get a chance to have him elaborate.
What does that mean?

 

??
I wonder if he is concerned about the centering pin on a double cardan, which you dont have on that shaft. It's three u-joints and a carrier bearing.