if this is the truck :
2001 TOYOTA 4RUNNER LIMITED 4X4 GOOD CONDITION
I wouldn't be concerned because it was a family car and has street tires on it.
Also if the frame is in good shape, the rear axel is a replaceable part so if it rots just swap it out with another one from a JY that would also be a good time to do a lift and all the rear bushings! LOL
still it is a almost 14yo truck that isn't extremely rare (except the KM's) for close to 10K!! these trucks really keep their value well....
*One thing though GET RID of that UGLY BUSH BAR if you buy it.
happy hunting