Toyota Previa SADS shaft caution when buying van

Howdy,
The Toyota Previa is a reliable vehicle and is built like the proverbial tank. The Previa is the model that preceeded today's Sienna van. You can obviously only buy them used. Take the normal precautions when buying a used Previa, the same precautions when buying any used vehicle.
There IS one very unique aspect of the Previa van. The engine is situated near the driver and passenger seats, set back from the normal engine position found in most vans. There is a shaft that runs from the engine to an assemble that is situated at the front where the A/C gepressor, alternator, etc. are located. The shaft bears the acronym SAD. I believe it stands for Supplemental Auxillary Driveshaft but when I owned a Previa and hung out at various Previa-related message boards everybody just wrote SAD or SADS. We knew what part was being mentioned.
A decent home mechanic can repair these shafts when they go bad but if your skills are lacking it can be very expensive to pay a mechanic to do the job. There are repair kits available to help avoid the cost of an entire shft but the labor cost is still there.
It is the thick rubber bushings that are part of the shaft that go bad. It seems that Previas in hotter parts of the country have the most problems with the SAD. Must be the heat wearing down that rubber. My SAD began to go bad at 130,000 miles. The Previa van can, typically, provide 250,000 miles of relatively problem-free driving so the SAD is often a cost-efficient repair.
However, if buying a Previa try do determine the condition of the SAD. Has the seller already had it replaced or repaired? Good!!! Just make sure you can prove that. If the Previa is from a hotter part of the country or has a lot of miles and the SAD shaft hasn't been replaced or repaired, it is safe to assume the shaft either now or soon will need worked on.....so, factor that in what the van is worth. Prices vary across the land for labor but I would consider a $500 to $800 reduction in a selling or asking price to cover the cost of the SAD repair.
As I mentioned, the Previa is a rugged reliable people-carrying conveyance. But, you gotta' be aware of that pesky SAD and plan ahead to cover that problem. You don't want to pay top-dollar for a nice van only to find out that SAD is going to require a hefty payment to bring the van to top-notch operating condition.