Bought both of my nissans with ~ 120K on the motors and wouldn't hesitate to buy one with 67k if cared for properly.

133K on my 90' pathy and the motor runs great. Replaced the torque converter last year on the tranny and all the gaskets so I expect it to last other 100k. Put in an aux tranny cooler at the same time.

124K on my 2k Xterra that runs near prefect, will be installing a aux tranny cooler with a electric fan, expect this auto tranny to last to 200k since Nissan has made some improvements

However, for 13K you should be able to do better than a stock 01 Xterra SE 4x4 IMO or get a price reduction.