Toyota Repair: Accessory drive shaft on 1992 Toyota Previa, drive shaft, imminent failure

Question
I have a 1992 Toyota Previa LE AWD with a bad accessory drive shaft at 160,000 miles.  This was replaced less than four years ago at 120,000 at the same Toyota dealership that now is diagnosing its imminent failure.  They looked at it during my state safety inspection today, said that the shaft was about to come apart.  Consequently, the van failed the safety inspection.  Please note that the same dealership only told me that it sounded like the accessory drive shaft may be going out when I brought the minivan in to have the front end repaired.  I erroneously believed the accessory drive shaft was primarily for the air conditioner and they did nothing to correct my mistake.  I would have certainly hesitated before sinking hundreds into rebuilding the front end had I understood the potential seriousness of the problem.

When I called Toyota, they said that the accessory drive shaft should not go out in 40,000 miles.  They said that even though the warranty lasts only 12 months, it would be very unusual for it to fail in less than 60,000 miles.  Toyota Corporation’s consumer telephone representative said that it's possible the shaft may not have been aligned properly when it was installed.  I don't see how a $900+ part fails so rapidly.  Are there forensic mechanics who can determine if the shaft has gone bad because of a manufacturer's defect versus misaligned installation?   I can’t expect my present dealership to provide an unbiased assessment of the problem inasmuch as they performed the work.

My registration expires in a week, so please let me know as soon as possible whether it’s even possible to obtain an objective assessment of whether the problem was in the installation or manufacture of the accessory drive shaft.  Also, what’s your advice about whether to repair the accessory drive shaft or get rid of the van?  Right now, I can’t see putting in repairing the shaft again if Toyota and my dealership service won’t back the repair for more than 12 months.  If I decide to repair the van, then should I have a different dealership do the repairs?  

Answer
As a matter of record, my 95 has 150K on it and still spinning.

The problem is they exceeded there warranty,wich is probably 1 year unlimited miles.So they legally dont have to do anything.
So they gatcha!
Thought for you. The squaky wheel gets the oil.
Pound your fist, politely, raise your voice, respectfully.
But DONT GO AWAY.
They know it should have lasted way longer, so does Toyota.
So I think if you keep at it youll at least get the job at 0$ labor.
The shaft can be rebuilt rather than replaced.

Mike